There Can Be Many Reasons For A Thing

John Cleese:

Good bye, Twitter

And thanks for dinner, Elon

— John Cleese (@JohnCleese) September 9, 2024

A bunch of other people (paraphrased):

OMG U USED TO BE SO BASED AND NOW UR SO WOKE AND WHY OH WHY R U BREAKING UP WITH ELON MUSK OVER POLITICS!?!

So far as I can tell (that is, on the basis of some quick web searching), Cleese hasn't specified why he's leaving Twitter ... or even if he is actually doing so. Maybe the post is just a belated notice of it now being called "X" by 1) Musk and 2) maybe one half of one percent of its users.

Let's assume, for the moment, that he plans to shut down his account and cease posting, re-tweeting, replying, etc.

Maybe he's decided Twitter just takes up too much of his time and that he'd rather spend his golden years doing other things without the distraction.

Maybe he's moving on to "compensated influencer" status on some other (new or existing) platform,  with this post as the amuse-bouche and a reveal yet to come.

Maybe he's moving to, or visiting, Brazil.

Maybe someone turned him into a  newt, and he hasn't yet got better.

The man is quite capable of making a forceful public political statement when he wants to. He hasn't, so why jump to conclusions?