Why should they be required to get into a fight they have no interest in and that is not tied to an objective? Players avoid fights all the time if they want to in games, why should SF be different?
Other issues that might apply:
They might not trust their GM to deal with them fairly and not want to risk getting an expensive starship damaged/destroyed. Do they have the means to immediately replace their ship?
They might be pursuing a goal and not want to deal with a sideshow.
They might not like the ship to ship rules.
Forcing the players to do things they don't want to do is a good way to lose players.