In the comment that got him banned, Advancedatheist said:

we need to restore a healthy patriarchy where women can't get sexual experience until marriage

just after he implied that lack of sexually available women was a viable explanation for two cases of mass murder.

I don't think it's "abuse of power" to obstruct the dissemination of such abhorrent views, especially at a website that has world-improvement as one of its central goals.