Everybody has heard MLK's "white moderate" quote by now so none of this should come as a surprise.
But obviously, the white moderates in question don't want to believe they're the ones being talked about, and they bully people out of Democratic spaces to preserve their comfort.
Marginalized groups have been discussing the flaws and bigotries among their white liberal peers for a long time. Getting mad about it doesn't do any good, but it does make you look like an asshole.