I've never said what happened was proper. I'm talking about how to avoid having it happen to you.
So are the Black Lives Matter protesters.
The difference is, you are blaming the victim of police brutality while the protesters are putting the blame squarely where it belongs - on the needlessly violent cops committing the brutality.
The best way to avoid being a victim of police brutality is to weed out the cops most likely to make you one, and to train the rest in ways to control a situation without escalating it into a violent confrontation.
Somebody can play a role in what happened to them without excusing what happened.