Socialists have never been class reductionists. Was King or Du Bois or Malcolm X?

Yes, Kendi's claim is analogous, and it is equally false. If it was, no one would reject capitalism or the class system.

Out of curiosity, who did you support in the last two US Presidential elections?

As for the class reductionist charge, Adolph Reed answers it:

https://newrepublic.com/article/154996/myth-class-reductionism