Schwartz was a joke. Really, I mean, if you see a woman being attacked and she is screaming for help then why on earth wouldn’t you help her out?! And why on earth would you just watch her and then walk away?! Or why on earth wouldn’t he at least try to get a good description of the attacker(s) and then run to the police?
I think the lack of action by Schwartz is what discounts him as a reliable witness. Any honest person would have gotten a good description of the attacker(s), helped out the woman, and then went straight to the police.