The author does seem to concede this at the end:


Yeah, but its causes are American society (and, in other countries, their society) when the extremists were growing up. We just can't change these people's basic fundamental bigotry or hatred. They picked it up before they were 20. No, deplatforming isn't a "one step solution", but it helps a lot. And I don't think it "accelerates" extremism; it's just that a long term change in attitudes of a lot of people is needed too.