Can't speak about USA or Alt Right, but a similar situation in Europe shows that the police are an instrument of the government, which serves a certain agenda and gives the police specific orders. Members of the police care mostly about keeping their job and it's a rare incident when someone objects the unconstitutional orders. It might be a different thing in USA, where constitution is still somewhat upheld.

And it's a joke that European governments declare their sympathy for protesters beaten in Belaruss, when protesters in Europe get brutally beaten all the time for objecting giving their land to "refugees" and becoming a minority in their land.

But if you speak about police brutality in the general sense, which is often a problem in many societies, certain circles, often in the far right, insist that people should shut up about it because for some reason you aren't supposed to criticize the police. The result is that police becomes unaccountable and disliked by common people.