Not long ago, an Iranian woman in my class told me that in her country, one had to be careful about what you said in public, but could say what you wanted in private.
“At Harvard, however, it’s the reverse,” she said.
This is the self-censorship some Harvard students complain of. Only some complain because the complaint is directed against the rest who dominate conversation and do not want to hear opposition. These dominant students may not begin as a majority, but the activist few create the majority who accept their view and then impose it on those who disagree, forcing them to censor themselves.
The punishment for not censoring yourself is to lose the company of fellow students and to be disregarded and shunned. You are not put in jail, as happens in Iran and other countries, but you are deprived of the fellowship you want from college life.