As someone mentioned above, some people are protesting peacefully while others are committing crimes and rioting. The concern is that police, and now federal agents, aren't acting in good faith and aren't interested in distinguishing between the two. It's possible to be concerned about abuse of power by law enforcement - which has been rampantly on display these past few weeks - without supporting anarchist attempting to set fire to buildings.

If we could know for sure the police weren't going to abuse their authority, there would have been neither protests nor riots.

Is it infeasible that rioters aren’t simply colocating with protesters to take advantage of the chaos like they have always?

The implication is the police are after the protestors rather than rioters, which is not observed.

I think that's plenty observed actually. When you look at who's been shot, beaten, and gassed it's largely protesters, not people rioting. Although it's easy for police to make the claim that it's rioters, since they seem to declare every protest a riot.