..Why is anti-China marxism so big?..
If you were a CIA operative, working out the details of, say, COINTELPRO, and knowing there is a substantial amount of Marxists and communist-leaning people out there... AND one of your goals was to demonize the AES states... Wouldn't you want to tear off a chunk of potential revolutionaries and defang them, turning them into armchair communists who never achieved anything and who always criticize everyone who did?
Bear in mind that a lot of those are in the West. Parenti spoke ostensibly about leftcoms/ultras (and left-anticommunism). This gets a few people off your mind, making the situation safer for the capitalist state machine at home.
"Neither Washington nor ~~Moscow~~ Beijing" shit