I don't know too much about POUM, but my understanding was that in Homage to Catalonia he's concerned with the Spanish Communist Party's suppression of POUM. So I think that is consistent with what I said above.
I haven't forgotten that Orwell was an anti-Stalinist socialist. But there weren't any anti-Stalinist socialist states at the time.
Indeed, communist repression of socialist ideas. I think the confusion comes from "surveillance of socialist countries in", where it should have been "Stalinist countries", not "socialist countries".