Let's be real. There really are certain people on the left who do some pretty skeevy stuff involving kids. Radfem Germaine Greer put out a book called The Beautiful Boy and had this to say about it:
I know that the only people who are supposed to like looking at pictures of boys are a subgroup of gay men. Well, I'd like to reclaim for women the right to appreciate the short-lived beauty of boys, real boys, not simpering 30-year-olds with shaved chests.
You also got the "drag kids". Last year, an 11-year-old known as "Desmond is Amazing"
danced in a gay bar while adults showed him with money.
Then there's the MAP community on Tumblr. AFAIK, most of them are on the left. Not sure if they're still around, though.
That being said, pedophilia isn't a right-wing thing or a left-wing thing. Anybody can be a pedo, no matter their politics. Hell, as you pointed out, there are some notorious cases on the right, even if I disagree with a couple of the examples you listed. And there are also plenty of left-wingers who've criticized other left-wingers who take part in this shit.