I'm all for criticizing Chomsky, but let's do it with a little more sophistication. He would agree with you wholeheartedly that the USSR, China, and so forth are repressive dictatorships. He rejects the use of violent revolution.
The criticism comes when we look at who falls into that category. Famously starting with the Khmer Rouge, he claimed that we shouldn’t believe the refugees escaping the killing fields. After evidence emerged he also famously never admitted he was wrong. He denies the Bosnian genocide, and most recently he has said such charming things as: “we should give Putin the benefit of the doubt” (regarding the Ukraine war).