Prequel is mo betta than a remake. You don't have to destroy the ship, there are many options to what could happen. The universe is infinite, an alien could be stowed away on a spacecraft humanity will never rediscover, the characters could encounter it on planet, it could even happen within the original derelict.
Space solves lots of the problems that a prequel would have.
A fox representative has nothing at all to do with SW, since that franchise is creator owned. Lucas could turn all of his characters into dancing teddy bears if he wanted, and fox couldn't say anything other than, "uuuhhhh George...we think thats a bad idea."