While I agree that Elon is petty enough to ban when slighted, it seems to me that simply running an older client version has too many other probable reasons to be clearly interpreted as personal insult.
One could reasonably argue that in some cases they were stretching the meaning of a rule, but they didn’t just arbitrarily ban users.
Heck, if there was one thing the Twitter Files actually showed it was the massive amount of debate and discussion and fretting that the powers at Twitter spent over most of their decisions.