When you say permanently select their sit and hover maneuver... you know that one is red right? At the least they'd have to do 1 maneuvers in between hovers, which for a large base ship actually pushes them forward a decent amount. I think you'd have a good alpha strike with that list, but I agree that you'd be in trouble once people start being able to get behind you. I don't think it's horrible though and would probably win its share of games, but I wouldn't call it overpowered or unkillable by any means.