I don't usually read open threads on SSC much; is it possible he's banning certain types of beliefs because they are overrepresented in his comments and banning low-quality posters of a viewpoint he thinks is already overrepresented does less harm to the discussion than banning people with more unique viewpoints? I remember he was at one time had an explicit policy like this for another group:

I’m going to be cracking down on comment sections a lot harder here in the near future. In particular, I want to cull the bottom 50%-90% of neoreactionaries. I like them, but I also like deer, and that doesn’t stop me from realizing that sometimes deer need to be culled. Having every thread with even the slightest opening turn into a full on neoreactionary feeding frenzy is tiring and driving other people away. I realize this is unfair, in that it’s not neoreactionaries’ fault that everyone else refuses to go to places where they are allowed to talk. Luckily, their whole ideology is that rulers have the right to optimize their territories for maximum productivity without regard for fairness to individuals, so I am sure they won’t object. Honestly I’d be pretty happy getting rid of everyone except maybe Nydwracu, Nyan, Konk, Athrelon, and Mai (apologies for inevitable people I forgot), but I won’t raise the banhammer until someone gives me at least a tiny bit of justification.