I know he died shortly after WW2 and the publication of Animal Farm and 1984, but the Cold War was already forming and there must have been warning signs for him. Did he react in any way to that phenomenon?
EDIT: the question can be extended to include any pre-Stalin socialist intellectual that later fought Communism more than they fought Capitalism. I find that trajectory really interesting.
The fact is he did rat on suspected undercover communists. You can count that as taking sides in the struggle between Stalin and the Liberal Capitalists. This wasn't an unusual choice amongst left pre-war intellectuals; take Irving Krystol, take Max Eastman, take James Burnham. Perhaps they found it more prudent to propagate their Marxian ideas under a liberal veneer. Perhaps they had no other choice. Or they did change their allegiance.
It's good to compare him to Brecht: The «Good Person of Sezuan» can also be read both with a Marxian subtext and as a straight Libertarian play. Before the HUAC Brecht was attacked as a communist and stringently denied that accusation. Still he had to leave, he was denied entry to West Germany and settled down in East Berlin.
Naturally, here he changed his attitude to his previous works.