If he was altruistically trying to save humanity from Twitter why didn't he just turn twitter off when he bought it?

I guess it could be because he didn't single handedly buy Twitter. IIRC he contributed $15B of the $44B acquisition. I guess he can't turn it off without his co-investors holding him accountable?

If that is his intention then he is doing a lousy job. Instead of simply shutting down the servers and never turn them back on, he has given other platforms plenty of time to rise, while loosing users to them little by little, this means communities can coordinate, trial and error, and get the taste of which other platform to migrate to, where they can continue this supposedly dangerous behavior.

If, on the other hand, he had simply shut of the servers many (most?) of these communities would have simply vanished for good, and many of their members might have been “liberated” from social media for good.