Some feel that Starfleet would not want to change anything about Solum because those events would have to happen or some temporal guideline supposedly would be broken or because it would be a fixed time loop, but I'm glad VA Janeway, at least, doesn't seem to agree with such a fatalistic POV. Of course Starfleet should try to learn what happened on Solum and, if possibly, take steps to avoid a repeat performance in this specific timeline.
This all managed to come to pass because the Protostar accidentally passed through a temporal anomaly in the first place.
Obviously, if the Protostar never encountered the anomaly, it would not have gone to the alternate future Solum where the civil war occurred and 'the order' wouldn't be able to set their 'trojan horse' plan in motion (they'd have to find, ambush and confiscate a lone SF ship elsewhere in their own timeline, and we have 0 clue if their ships would be able to do so in the mid 25th centur).
So, when it comes to temporal manipulation, one could say that because this was an accident, and Chakotay is still trapped, SF would be obligated to try and save him... either by finding the anomaly and targeting the specific temporal coordinates so they exit at the time a bit after Chakotay launched the Protostar and 'the Order' launched their ships in pursuit, or they would have to wait until the early/mid 25th century to go to Solum and rescue Chakotay.
Who knows, maybe the initial First Contact with Solum was an early attempt to try and locate where Solum was (to try and rescue the Protostar crew when the time came to do so), and when they realized they made contact with the Vau'N'A'Kat, it was too late to change things, so they had to follow FC protocol.
Basically, a predestination paradox issue.
The Protostar travels accidentally to ruined future Solum, but the FC with Solum was made because SF was looking for it in the first place so they can be ready and rescue the Protostar crew (I don't think it was established WHERE Solum is, just that its somewhere deep in the DQ).