I think these things are indisputable:

1) He was concerned with demographic replacement of the West.

2) He had a particular disliking for Islam.

3) He had a trollish sense of humor (Spyro the Dragon, "subscribe to pewdiepie," citing Candace Owens).

4) He was far-right.

I think the mentioning of the Chinese was mostly to stir the pot, while agreeing with China being mostly ethnically homogeneous. I doubt he cared about other things such as social scores, communism, and whatnot.

As for him being a former communist, well, that was likely when he was younger and that's what the propaganda wants people to be.

I doubt he really had much help with the manifesto -- it wasn't amazingly written. The Unabomber's Manifesto was far more hard-hitting. It's not hard to be far-right and see what motivates the left, a simple conversation with leftists will do the trick.

His motivations were primarily accelerationist and to provoke the left into being more tyrannical. For example, Fabian socialism advocated for incrementalism to avoid upsetting people. His goals were to counter the slow trickle of the leftist utopia that leftists use via brainwashing, social engineering, and censorship. It's like putting the frog into water and having it jump out only when the water's temperature changes too quickly for it to notice.