>>edgyqu+6a
That would be my general theory as well, you're far more likely to meet someone who is left leaning who admits to having posted on 4chan (or still does) than you are otherwise. Maybe it has to do with perceived biases, in that a right leaning person/group is probably then going to feel they are aligned with the seediest aspects of 4chan, whether they actually do or not and their perceived social impact/failings for using 4chan.