I am relatively new to diving, but this is something I know a little about. The owner of the pit bull showed several instances of exercising poor judgement. I'm not sure what they are in your community, but most communities have leash laws. Most of these laws require that owners keep their dog(s) under complete control at all times. If his pit bull had inflicted any harm to you or your dog then he would have been financially, if not leagally responsible. To take an animal out into the public that shows tendancies to be agressive and on top of that, not have complete control of that animal is ridiculous. He should have been issued a citation for not controlling his dog (a hit in the wallet like that tends to make people pay more attention). Unfortunately even if society idiot- proofed the world, God would create the better idiot.
I hope that this incident wakes this owner up as to the proper way to keep his pet & the public safe.