"I understand that on some level putting Peretz in jail was a reasonable response to him not leaving the scene, ..."
It sounds completely unreasonable to me, by the way. Of course he doesn't want to leave, he just found someone bleeding in the street, it's natural to care about what happens to them. Why should he leave?
And why would he go to jail after not obeying immediately? Isn't there something else that you guys get in a case like that -- a citation or what have you?
I was told to leave a scene not so long ago, when they frisked a group of immigrant kids (and in the end took away one of them who apparently had some drugs on him; so actual police work as opposed to a traffic accident). We didn't. We stood back a meter and observed. After that, they didn't take down my name, I certainly wasn't manhandled. That seemed reasonable to me.
The hostility -- the sentiment, not the actions following from it -- displayed by the officers would be understandable (if pathetically unprofessional) if he had been drunk and belligerent. But that's not what he says happened. And I'm inclined to believe him, since he wasn't charged with anything.
Edit: Added that anectode, sorry for stealth editing after upvotes, hope nobody minds.