Regarding the planet in SNW: I would hope the Federation made sure that no such problem would arise on one of their member planets, even if a UN-style intervention would have been necessary. I doubt the results would have been worse than what happened on the planet Tasha Yar came from, where the UFP did not interfere.It would cost them resouces though, as investments would have to be made and a de-facto military force may have been needed so that certain limits could have been enforced, even if only on stand-by as a potential tool without any actual use.
Point being, we don't know what happened on that planet... and I for one would think the UFP would NEVER try to leave a 'military force' as a 'detterant tool'... because it doesn't sound like UFP or SF... and it would seem forced.
I was merely positing as to WHY the UFP introduced entry requirements for joining (aka, a planet needs to have a unified government, no discrimination, no caste system, and has to be Warp capable - there may be other requirements I may have missed, but these seem to be top ones).
Its possible that after the brief euphoric moment, some people on that planet started causing problems which could have led to a civil war.
In fact, I wouldn't be surprised if SF DID try to interfere and it caused more problems down the line for the society in question.
And there is also the point of supporting allies within other species (not necessarily members), which the UFP usually also doesn't do. I can think of at least one case were this did not appear to be beneficial: Picard's initial refusal (backed by the regulations, of course, as it is/was the official policy) to back-up Gowron (despite the other claimant being hostile to the Federation and being revealed to be a Romulan puppet, on top of being a personal enemy of Worf) IMO resulted in Gowron losing respect for the Federation and indirectly led to the brief Klingon-Federation war in DS9. It could have been much worse had Picard not found a loophole to kinda/sorta support him anyway, but that was only because a combination of cicrumstances allowed him to expose Romulan involvement. I question if the UFP's strict adherence to non-interference policy, no matter the specific circumstances, is wise.
Backing up Gowron was not possible. The Klingons were in the midst of an internal conflict - and SF has a strict policy to NOT interfere in internal matters of other societies,
Also, SF didn't exactly sit this one out entirely. Picard and the UFP were investigating how the Duras family suddenly become so powerful and where they may have been receiving the supplies from (which turned out to be Sela/Romulans).
If you recall, SF acted in a similar way during DS9's run. Bajor had some internal issues during those 7 years of its recovery, and on some occasions, it was pointed out that SF couldn't interfere in internal Bajoran affairs... however, some of those problems had an external cause, and they were directed at SF... so those were investigated and brought forth to the Bajorans as evidence when stopped/exposed and SF/UFP left it to the Bajorans to decide on what to do.
Same thing happened in TNG. Picard may not have supported Gowron, BUT, he DID expose the Romulan involvment (which Gowron DID recognize).
Also, Picard went on a limb for Worf who was playing a bit too loose with regulations at the time if you recall.
We don't know how many Vau N'akat survived, but I think it was not too many considering how few people they sent on their last remaining ships and how angry the survivors are (I also did get the impression, from Ascencia's story and visuals of the planet, that destruction was widespread). The Diviner knew well enough he and Gwyn weren't the last (not only considering the survivors in his timeline, but also the existence of an as of yet untouched Solum in his new timeline), but even so he seemed to consider the fallout of the civil war (in his timeline) and the threat of first contact (in the new timeline) to be dire enough that the Vau N'akat might not survive as a species.
The Vau'N'A'Kat survivors could still number in millions on both sides.
The civil war may have destroyed a lot of their Living Constructs and ships, which is why the Order appropriated the final 100 ships to look for the Protostar in the past.
We hadn't seen the full extent of the fallout on Solum, so we cannot be sure how many Vau'K'A'Nat survived (man, the name of the species is TIRING to type accurately) one way or another until this storyline is explored more in full.
The conflict was devastating (that's for sure)... but possibly not species-ending event.
I'm not sure if Ascencia's faction was particularly xenophobic against alien life, per se. We know virtually nothing about the underlying causes of the conflict and the structure of Vau N'akat society. It could be they were very authoritarian and it was not the alienness, but the relative equality within the Federation (even though Earth, and I suppose Vulcan and maybe Andor, are likely top dogs within the Federation) that caused the spark.
It was explained fairly well that Ascencia's faction was pro-isolationist. The Diviner himself stated they thought they were alone in the galaxy and universe at large. The arrival of SF (aka First Contact) shattered their preconceptions and caused a split on Solum.
Seems to me that the opposing party was fairly anti-alien (aka, xenophobia would enter the picture to a degree at least).
As for what the Federation should do: that should depend on context, not on an iron rule of which no deviation is possible (though several captains circumvented the prime directive when it suited them). In any case, letting a civil war happen because it could make the involved society better potentially, would be a very bad motivation for non-interference.
If they genuinely thought interfering would make things worse, that's another situation (though in that case they were probably not right as the actual outcome was very, very bad for all parties involved).
You realize of course that SF had no way to predict that initiating first contact with Solum could result in a civil war, right?
Basically, what SF did was say 'Hello, we are explorers from UFP which is in another part of the galaxy. We come in peace and were wondering if you might be interested in an exchange of cultural information perhaps?'
Solum's response: 50% - wow, there is sentient life elsewhere in the galaxy, and the UFP is an interstellar alliance that encompasses over 150 member worlds living in peace and prosperity, freely sharing resources, science and technology with each other?
The other 50% - what? there is sentient life elsewhere in the galaxy? What the heck? How is this possible? It can't be. I don't like the prospect of other alien species, I'd prefer to live in seclusion without being bothered.
Basically, that's what it boiled down to. In the end, the reciprocal half of Solum wanted to join the UFP, but the other half did not, and this caused the civil war.
SF opted to NOT interfere in what is clearly an internal conflict the Vau'N'A'Kat had and which they themselves had to resolve, because otherwise, what exactly could have been done?
But I suspect it may be more likely that, much like Picard with Gowron, they simply followed an ironclad rule and they may have left their allies among the Vau N'Akat out to dry - and to be slaughtered or converted, as the Diviner apparently was.
SF didn't abandon Gowron or the Klingons. They helped them in another way because there was an external influence (from the Romulans) that caused the problem within the Empire... this is why SF was able to act on that particular matter.
The conflict on Solum was basically something that arose internally due to Solum's perceptions (and personal sense of superiority) that they were the only intelligent species in the galaxy (and possibly the universe) and direction where they should go. In effect, they weren't really ready for first contact.
Usually when a species is already advanced and has FTL ships, it is presumed that they might actually be able to handle the concept of alien life and be able to settle their differences without involving others.
Maybe SF DID offer a solution in the way that they LEFT and allow Solum to reconcile its differences in time - that was in effect the only viable option for them to do.
The isolationists didn't want to join UFP... so SF thought the best thing to do would be to withdraw, because otherwise, doing something else probably would have caused further problems.
Would you like to be drawn into a conflict as a third party knowing full well that whichever choice you might make, someone will end up very unhappy with it in the end and blame you (permanently souring your relationship with them?).
I was presented with this dilemma as a kid when my two cousins ended up in a heated argument against one another... they asked me whom do I like better... I told them I have no real preference, but they weren't happy with that and tried forcing me to decide... so the best thing I could do was to tell them to work out their problem among themselves and leave me out of it - turns out, their mother and my grandparents all told me I made the right call and that they should have never brought me into their 'dispute' like they had in the first place.
Here's the thing... in that kind of a situation, nothing you do will probably give satisfaction to everyone... that's why 25th century SF withdrew... they could NOT involve themselves further because they probably knew that anything they do will have lasting reprecussions and could set a terrible precedent when it comes to the Federation at large.
Gwyn and the Prodigies are technically still not part of SF, so even if they DO make some kind of change, it could very well be on the 25th century war Solum (because that's where the problems started, and that's where Chakotay is at).
Its also possible the Vau'K'A'Nat also have few other internal issues to resolve first (which may have been festering), and encountering the Federation simply ended up setting it off (similar to what the Kyirians and the Vaskans underwent in 'Living Witness' on their planet - even they eventually figured out that they had to resolve their own differences and that the truth of what happened in history has to come out and they need to learn to live with it, however 'bad' it may have been).
Civil wars aren't pretty... I don't want this to occur in reality as its utterly pointless/sensless loss of life that arises out of ignorance and due to outdated socio-economic system we have in place which is full of outdated values/ideas, etc.
However, for Solum, we have to accept the possibility that this is something the planet may have to go through either way in order to eventually grow as a species...otherwise, they wouldn't be able to move forward and will be stuck.
Besides, The Diviner told Gwyn that maybe she could unite the Vau'K'A'Nat in a way he never could (right before he died).
Just how can Gwyn be expected to unite her species when there's (presumably) no division as of yet in 2383?
Or perhaps it will be revealed that the division on Solum existed well before SF made contact and that the opposing Vau'K'A'Nat in the future were just blaming SF because they were blinded by emotions.