I think you gotta give Campbell some more snaps if its just a bruise with minimal swelling. If that is the case, he cannot make the injury worse by playing on it, albeit for a little stiffness/soreness. You can't shut down essentially a rookie QB after week 2 of the preseason just because he narrowly evaded a catastrophic injury. We got lucky, everyone knows it. Gibbs has the right idea. He needs to play if he can. Every snap is critical for his timing and confidence. Even if its just a couple series per game for the final two weeks.
Also, gotta think that Campbell walking away from that is a sign of something special to come