"Cultural Marxism conspiracy theory" is about claiming that said post-war academic movement is a "Jewish plot". Yes, that's an antisemitic conspiracy theory. But stating that the academic movement exists, and discussing to what degree its ideas influenced contemporary social movements such as BLM, is not a conspiracy theory, and not per se antisemitic.
I think what is happening here, is some people are motivated to ignore the difference between what is a reasonable argument ("to what degree was a contemporary social movement influenced by a contemporary academic theory") and what is an unreasonable one ("it's a Jewish plot"), because they want to shut down that reasonable argument
Did you bother to look at the sources? https://newrepublic.com/article/144317/trumps-racism-myth-cu...
Good stuff.
https://en.wikipedia.org/wiki/Cultural_Marxism_conspiracy_th...