Well Sam Marcy himself came from a Jewish Russian family that was a target of the pogroms during the Russian civil war. They ended up escaping Russia with the assistance of the communist forces. That probably colored his impression of the USSR for the rest of his life, since although he would criticize Stalin and Soviet bureaucracy, he always regarded the USSR as legitimately socialist and a defender of workers' rights. Also you're right, every WWP member I've met has been lovely. It's kind of surreal sometimes because a lot of them in my area are older white people, yet they're very rabidly pro-China, and that's just not normal at all to see in older Americans lol.

So from the outset the WWP was weirdly pro-Soviet while also being Trots. The Marcyite movements were like reverse splitters. Every time they split they became more ML. The WWP initially split from the Trotskyite Socialist Workers' Party over support for China. Marcy, Copeland, and the members they had cultivated all had a positive opinion Mao. PSL would eventually split from WWP and there's not a whole lot of literature on why. But I've asked around and it seems to have been a split in desired tactics among certain members of the leadership, and it wasn't a split over ideology. This is anecdotal, but I've been told by some older PSL members that the idea is WWP wanted to continue being more structured like a Trotskyite party. They wanted to continue the tactics of street protests, newspapers, etc. whereas some of the initial PSL members wanted to be more like a coherent electoral/political party that was directly structured after the Communist Party of Cuba.