[7] Communism promised to be both morally and economically superior to capitalism, but every attempt became morally corrupt and an economic failure. As it became clear that the working class of the liberal democracies wasn’t going to overthrow their “capitalist oppressors,” the Marxist intellectuals transitioned from class warfare to gender and race politics. The core oppressor-oppressed dynamics remained, but now the oppressor is the “white, straight, cis-gendered patriarchy.”
I can find some meaning in his footnote which isn't anything like a dog-whistle. He is saying that the group of people fighting for a economically left system changed tactics. Instead of arguing about class, they are coopting gender and race to try to change society. I'm not sure I buy it, but it's reasonable to suggest.