It’s not really about privelages, more so the fact that Staff Officer is (occasionally) a deployed combat role, where Auxiliary Support Officer isn’t.
ASOs cant drive the ARC, because the ASO is a shipside-only role, barring Nuclear and Delta alert, and even then, they cant leave the FOB
It just doesnt make sense to give them access to a big vroom vroom shooty shooty, if they aren’t allowed to drive it anywhere of use