Jacob Schiff the Wall St. banker is also very notable

Probably motivated out of some sympathy for Russian and Eastern European Jews due to the whole "pogrom" thing. That aside, the Russians managed to lose that war just fine without outside help. They'd actually managed to hold the Japanese army, but with their navy gone the result was inevitable.

various anti-racism policies

Russia was a multi-ethnic Empire and the Communists gained a lot of support via promising equality to these groups. Commies gonna commie.

These kinds of policies were only removed once Stalin had total control over the Soviet Union, at that point they were no longer needed.

Or there was no one left to oppose him. Stalin had some pretty brutal intentions for the USSR's Jewish population, and was stirring up the sentiment he needed (Doctors' plot) to gulag them before he died.