There was an interesting essay by Emily Parker in
"It's just become so taken for granted that it isn't even recognized as self-censorship. Three or four times a month I get questions from students: How can I avoid getting on a blacklist like you?" This quotation comes from Perry Link, a
"There are writers I respect who don't choose certain subjects because they will engage them in controversy with China. Visa denials seem to be based on the subject matter more than what the individual says about the subject" (Jerome Cohen, New York University).
The idea that scholars "collectively are compromising our academic ideals in order to gain access to China offends people intellectually, but we all do it" (anonymous professor at a prestigious American university).
PS: The excellent illustration that accompanied the essay is by Yarek Waszul.