Should you be committed to the move?
I feel it fits thematically and game play wise it makes sense(to me). You hit the boost button and you clip a rock, why would you get to undo that decision?
Boost could be used/abused to not get shot if you miss your mark, I get that but you could always add the rule that if you boosted into a ship you roll for a damage. 1 on a crit?
I feel it would add more to the game without there being much of a downside. It would certainly be no more abusive than ships using it to see if they can 1 bank the next turn safely.
Slam is practically the same in a sense and you have to commit to that, it's just a more extreme version.
Thoughts?