“Cultural marxism” is a ridiculous, made up term by some conservatives who wish to undermine the language of critical theory and The Frankfurt School. It is a pejorative invented by the alt-right to insult right-wing liberals, while also dividing the left.
Adorno, one of the key members of the Frankfurt School, shut the door on student activists in the ’60s for abandoning true leftist politics in favor of blind activism.
Marx himself championed “ruthless criticism of all that exists” and we can deduce from this that he would likely have been critical of safe spaces, too.
“But, if constructing the future and settling everything for all times are not our affair, it is all the more clear what we have to accomplish at present: I am referring to ruthless criticism of all that exists, ruthless both in the sense of not being afraid of the results it arrives at and in the sense of being just as little afraid of conflict with the powers that be.”