Those are the same type of people that would have interrupted Jesus during the sermon on the mount. Jesus would have been like, "blessed are the poor" — "No, Jesus, blessed are all people".
The target of his joke are people who insist on correcting the formula black lives matter to all lives matter. Of course all lives matter, he says, and since black lives are an especially vulnerable part of all lives, let's focus on them. But to illustrate this point with that particular reference to the sermon on the mount is a bit ironic. Wasn't the original intent of the blessed are the poor message precisely the opposite — that the poor are blessed as opposed to the rich? Camel through the eye of the needle and all that?
I realize that protestant churches have gone through a lot of effort to transform the early Christian message into a more comfortable and progressive one that says that wealth is a sign of god's blessing; but it still amuses me to see how deliberately people pick and choose words from the Bible.