It reads like he received this viewpoint from a Marx-sympathetic university course that nonetheless could not fully endorse Marxism for fear of people complaining that they're turning people into commies

For sure. Marxism in social science 101 is viewed as this esoteric hyper-specific framework that is only about class, and besides, class isn't real anyways because middle-class! 101 likes to focus on Marx as if no-one has ever continued his work. Alex seems to know that, since he references Angela Davis and black marxism. Though Angela Davis did support Harris when she became VP, so I guess maybe its just the radicalized nature of modern US marxism.

But saying that half the people telling you not to vote for Kamala are Russian bots is just peak radlib Tumblr/Reddit, and is disconnected from reality.

I had the same feelings about it. I feel like he is only interested in the abstract/philosophical aspects of liberalism and marxism (ideologies in general maybe), without actually applying analysis to current material conditions. His brief comment that Reps and Dems are both liberals is completely neglected in the end section.