From the very start, in my games, I always assumed that the easiest and one of the most common forms of piracy was to program a false course into the ship's computer. The navigator checks that - if s/he is one of the bad guys you are SOL. Also, in emergencies, it takes navigation expertise to override the safety cutouts. The ship's AI knows it is too close to a planetary mass, and won't do it. That meson gun shooting at you is not the AI's problem. While Navigator is usually a collateral duty, and the party can get by for long period without one, eventually they will wish they had someone with lots of points.