jankom was ready to tell, but the Dauntless's Doctor pushed jankom's personal self-image buttons and distracted him. (the whole show we've seen that he's touchy about self image and reputation, so being dismissed and told his name meant "runt" was certainly going to set him off. especially after he'd built up the image of federation tellarites as special.)
Dal was ramping up to it while struggling with hero worship turning him tongue tied (a common thing with kids and adults), before being interrupted. while you can question his decision to run away after the denobulan was brought over, he made a choice that a lot of people would. to avoid a confrontation where he'd be accused, yelled at, and arrested before he had a chance to get a word in.
Gwn was ready to start in, but then found out that the starfleet ship had her father, with a friendly relationship between him and them, which immediately made her suspect that they weren't going to listen.
the kids didn't really get a chance to even introduce themselves, much less segueway into a discussion of why they are trying to get to starfleet and what is going on. they can't exactly just walk up to a strange starfleet officer and go "there is an alien weapon on this ship i have that will destroy the federation". at best the starfleeters are going to ignore him as a crazy person, at worst they're going to assume he's making a threat, arrest him, and go to check out his ship and stop the weapon.. and pretty much every response inbetween tends to end with "then the starfleet crew goes to investigate the protostar, and triggers the weapon."
the only way that they'll be able to get across the danger without coming across as either insane or hostile, is to introduce themselves, explain how they learned of starfleet and explain their recent history, then explain what the weapon is and how they learned of it. which is something that will require a lot more than a few sentences to a stranger they just happen to stumble over.
prediction wise, i'm guessing that the kids will end up using Okana as a messenger, telling him their story (and perhaps providing non-digital copies of various evidence, like photos and printed files) and dropping him off somewhere that he can be found by Adm. janeway. but before that the Diviner will regain enough of his memories to remember what his mission was, and will start manipulating the crew of the dauntless into pursuit of the protostar, likely by 'confirming' the story that janeway already suspects.