It is entirely possible that he's had some unhappy interactions with Enworld. While I have participated in some interesting discussions there, a few times I have seen people make not-so-terrible and thematically appropriate comments and then get told "we don't allow that kind of talk here" by moderators.
I blame the site owner (Morrus) for this. Just the other day, someone brought up the topic of AD&D 1E having Strength modifiers for female characters (getting the details wrong, as usual), and he quickly showed up to shut the tangent down, saying that "that isn't inclusive game design, and we want EN World to be an inclusive community."
Honestly, I'm not sure if Morrus has always been like that, or if something changed. I say that because I heard second-hand reports about how, several years ago (2008 maybe?), there was a pretty major incident on the forums. From what I heard, someone made an
incredibly offensive, but calmly written, statement on the topic of rape; this in turn received a number of very impolite responses.
The kicker here was how the moderators responded. At the time, posts were moderated for tone, rather than content (notwithstanding a blanket ban on politics, religion, and profanity), which meant that the mods were deleting the fiery responses while leaving the original, offensive post alone since they weren't sure if it was in violation of the rules or not.
As such, people saw that the mods were leaving the offensive material alone while deleting the responses, and
shit got real. Cross-forum attacks happened, where members of certain other forums (I never got an answer as to which ones, but it seemed to be The Big Purple and SomethingAwful) began mass-registering at EN World so they could heap abuse at the mod staff there, with an emphasis on Morrus in particular. It got so bad that for a short time the site removed the ability to register new accounts.
When the dust settled, Morrus had been thoroughly beaten; the offending comment was removed, and he announced that the topic of rape would now be permanently banned from discussion. If he wasn't on the road to SJW-dom before that, he certainly seemed to be from that point on.