If bringing up certain claims against the leaders of a BLM chapter are enough to delegitimize their message (well, a message over 400 years old as someone said). Then, police, in this case, have no defense. And people should have no problem coming at that institution with 10 times the fervor. But it doesn't happen.
And just as a note, I always hate the proposition of "we need to come together" and then the responsibility is laid equally on both parties, when it's quite obvious there's a difference in strength. It's comparable to Demetrious Johnson fighting a newborn infant. It's not a fair fight. So, when talking about "coming together" you must proportion 100% of the responsibility appropriately.
Making jokes about accepting checks while people are brutalized by police just shows a level of detachment which is one of many reasons things are difficult for minorities.
First, it's police, second, it's inaction and third, it's those who are putting the marginalized on the same level as police; i.e. making them responsible for their own oppression.