Elon has been so hands-on and vindictive that it's hard to rule out him personally deciding to ban pg and then going back on it, but that's not the only possibility. If you looked at the replies to pg's initial "I'm leaving" post, there were hundreds or thousands of Elon's reply guys mocking him or deriding the decision. Twitter has become much more of a toxic hellhole than it was before.
What I've noticed is that accounts tend to receive bans when a large number of users report them simultaneously (whether they are actually rule breaking has relatively little impact). It strikes me as possible that a bunch of Elon's fans reported the "I have a Mastodon account" post, and some moderator pulled the plug on the account on the assumption that that's what Elon would want.
To be clear, I'm not saying any of this would exonerate Elon. He put this stupid policy in place to begin with. If anything, the sheer scale of the pro-Elon toxicity I've seen in every Twitter link I've clicked today is a symptom of a much bigger problem that is slowly building on the platform.
I think what's highly likely is that the "hundreds or thousands of Elon's guys" (or 4chan trolls) reported the account/tweet.
Most platforms use some sort of automatic algorithm coupled with an army of people in "third world" countries doing actual first-level reviews and a smaller group people at HQ supervising/monitoring/working on the algorithms.
Well, except...he fired all those people. So now it's probably just "autoban and if there's enough noise, someone comes back and unbans."
When the elon jet reddit user got banned, it was probably the same thing - trolls/bots/muskies mass-reporting after a post hit the front page.
It's not so much whether or not someone you like Paul Graham or not. I don't follow him. I don't know him. I'm sure he's a fine person.
But if you really, truly believe in free speech and having a platform for sharing interesting ideas, then you want someone like Mr. Graham on the platform.
https://twitter.com/elonmusk/status/1604616426114932737