Our society is not without faults. Our domestic and foreign policies are also often flawed. To correct failings, we need people who point them out, however unpopular that may be. We should be enabling a wide framework of public discourse, not seeking to silence people. To date, we haven’t quite reached the level of hysteria of 1950s McCarthyism, but we are perhaps coming close.
It’s more the idea that a lot of communists have that “anything that challenges American global hegemony = automatically good.”
Colloquially referred to as “Tankies”. America = Bad, therefore Not America = Good mostly sums up Tankie takes, but more properly Tankies is a pejorative for authoritarian communists, usually apologists for China and the CCP nowadays. IIRC originally it referred to communist parties in Western countries that excused Soviet actions during the Prague Spring and such, although I’d say that is an obsolete term.