I wouldn't say that it's an ad hominem quote. I disagree with the premise - that censorship is a "default position regarding so many things" within progressivism - but I think that the link between censorship as a default position and a fear of the survivability-under-discussion of one's own ideas is a rationally visible one. Unlike a typical example of an ad hominem attack, the undesirable behavior (fiat elimination of competing ideas as a default response) is related to the conclusion (that the individual is afraid of the effects of competing ideas). It's oversimplified, but one can say only so much in a short quip.
Would the term "genetic argument" be better, do you think? Fewer emotional associations, certainly :P
Anyhow, what I meant to indicate is arguments of the form "Person or group X's argument is wrong because X has trait Y." Example: "Rossi's claims of fusion are wrong because he's been shown to be a fraud before." fits this category. Rather than examining any specific argument, we are taking it "to the man."
And I agree that these arguments can absolutely be valid. But if there is any kind of emotionally-charged disagr...
Another month, another rationality quotes thread. The rules are: