I mean, he explicitly references anti-Semitic conspiracy theories as his source at multiple points. That alone is enough to completely undermine his credibility, leaving aside the myriad other problems with his memo.
Quote: 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.”
Or is that one ok because it hasn't been debunked?
In which case, according to Wikipedia, the Frankfurt school "consisted of neo-Marxist dissidents uncomfortable with existing capitalist, fascist, or communist systems." Has that been debunked? If so, where?