Yes, you're correct. But they're far from the only people who have jobs dealing with profoundly uncooperative people, and we do not accept violence from other professionals regardless of what they encounter from the public. I believe that police work is something of an exception, but only a limited exception: by and large I expect (and demand!) that they handle stressful situations without resorting to violence whenever possible, even if that is uncomfortable or stressful to them.
> I can see a good argument that if someone throws a brick the police should be as targeted as possible in responding. But it could easily be the point where a crowd disintegrates into an unruly mob and the police would have my total support for not being optimistic and trying to push into the crowd hoping it works out OK.
This is important to talk about - I think what myself and others are calling for is a targeted response by police, and what we've seen over the past few days in America is that the responses are overwhelmingly not targeted, nor are the appropriate. (Not to mention the fact that there is now ample video evidence of police responding with force when there was absolutely no danger whatsoever).
Essentially, it seems as though the police are taking the second part of your assertion to heart - that it's okay to just be indiscriminate when there's danger - but vastly over-applying it and labeling completely benign interactions as "dangerous", and using that to justify their use of force.
Again - I invite you to consider this through less of a theoretical framework, but through the lens of what we're seeing unfold in front of us: police aren't treating legitimately dangerous mobs with justified violence; rather they are treating all protestors as if they are an unruly mob and applying violence indiscriminately. And that is a very large problem.
> If someone in a crowd is throws a brick at them
As a parting note, there is really not much brick-throwing going on. And given the demonstrated propensity of the police in America to lie (despite video evidence), please treat their claims that people are throwing bricks with extreme suspicion.