He has a long history of making statements like this. Anyone showing up for the first time in years only to intentionally and obviously violate rules should be kicked out.
I fully agree with the idea that "ethical" licenses aren't free software, but the dude is a terrible actor in this. He violated the rules, and got banned. That's not a bad thing!
I don't see any evidence that he violated the rules; he described Coraline Ada Ehmke as a "toxic loonytoon" as part of his opposition to her ethical beliefs. Whether or not he is correct about that, I don't see how it's a violation of the rules to say so — it's not as if he used a slur against women, white people, or transgender people. Even when he railed against "Marxism" (it's not clear to me whether Ehmke is a Marxist, but certainly some of her supporters are) he didn't use slurs like "commie" or "tankie", despite the bitter hatred of Marxism that his life is oriented around.
For the sake of fairness, consider the case that people opposing him would use similar lunatic language.
They would drop fighting words like neoconservatives, greedy capitalist, far right nuts into the discussion. That would be crazy just as well.
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For the record, I think ESR was mostly right on the issues. He is just communicating like lunatic angry person.