Well, to be fair, America is a majority-white country, so pretty much any mass movement — certainly including the progressive movement — is likely to be majority white. (Have you seen a Bernie Sanders rally?) But Nichols’ pivot to racism and talk of “the obsessions of white anxiety” provides a clue to what’s going on.
Moral superiority is an addictive drug, and perhaps the most unfortunate legacy of the Civil Rights era is that it got people on the left dependent on moral superiority for their self-esteem. It was easy to feel superior to the likes of Orval Faubus and Lester Maddox, and it felt good.
But once you become dependent on moral superiority, you need moral inferiors. Thus, every issue must become one of great moral urgency, in which the people who disagree with you are not simply wrong, but actually evil.
It’s even better if you can think of them as being stupid as well, since that lets you think of yourself as smart.