I know that every day a cop goes to work there is a big 'What If" hanging over his head but that doesn't give them any right to beat the crap out of anyone they feel "could be" a suspect.
I once passed out piss drunk sitting up in a livingroom chair after a party at my house. Then someone entered the house, sat on my lap and started slapping my face repeatedly as hard as they could. In a spilt second (I know this from the witnesses) I picked that person up and body slammed that person onto my living room floor. After that it took me a good minute to realize where I was, who that person was and why they were lying wincing in pain on my floor.
So I can see why the guy in the sleeping bag reacted that way.
I think the problem stems from COPS being there. Seems like they always try to be a cowboy for the camera. Ever notice how it takes 6 cops to cuff a skinny guy slurring "what, what?". These officers probably would not have acted this way if the cameras weren't rolling.