My complaint was more to your second point, that "If the complaint is that his work is spreading to, or being adopted by the anti-SJW crowd, that's hardly his fault." I do see a problem with how one-sided the comments on the page (Heterodox Academy) are, and I do think that he should have stepped in. Then, when I came to Hacker News, I saw similar comments, and that was disheartening.
My distaste really came from comments like these, on the main page: "My white male sons are now 30 and 28. I’m so happy they escaped public high school relatively unscathed, but I could see the beginnings of the nonsense, led by a faculty of activist females and male eunuchs. Public schooling in this country may have begun with noble intent; kids are now truly being inculcated rather than educated." and "You state this like it is an article of faith that women would be totally rad in STEM if only men would stop holding them back. What makes this “sketchy”? There is an abundance of evidence that men and women are different and think differently. There is almost no evidence that women will change that position based on upbringing." and then on hnews itself: "#KillAll(White)Men is literally calling for ethnic / gender purging." (though it was downvoted).
It would be great to have a conversation with Dr. Haidt, but I was turned off by how both Heterodox and Hacker News turned into "amen" forums. There were two students who posted on Heterodox, and they had some interesting points, some of which disagreed with Dr. Haidt.