I recall when the Daniel Shaver murder happened, a lot of the same people who now criticize BLM were criticizing Shaver for not listening to the police, or saying he deserved what happened to him, and objected to the idea of police brutality existing at all.
Wrt Daniel Shaver, from my experience, most people that I know just didn't care very much. It's sad, it shouldn't have gone down like that (much like many other instances), but at the end of the day, there's only so much emotional bandwidth to spend, and it can't all be allocated on everything at the same time.