It's a private space. He can do what he likes. We draw conclusions about what we think, but thats going to good-or-bad justified-or-unjustified consistent-or-inconsistent as matters of opinion.
I note that he said he wanted a space with less constraint. He said it quite simply and directly. He's capable of both changing his mind, and in believing this is consistent, and in not caring either way.
I left twitter some time ago. Long before Musk's offer to buy kicked in. I think this is a fight amongst people I have little in common with.
This isn't really a "who cares" post because it is interesting. And arguably important. Mostly it's importance goes to the problem that Musk is now overtly in Politics, and has declared his non-neutrality in the US domestic political sphere. If he hadn't done that, I think there would be little more to remark on here than when Jack Dorsey did mildly irrational things. But a declaration to partisan views in politics changes that somewhat: he has control of a massive media machine in a politically charged context.
It is theoretically possible the FTC and the FCC both are looking at this wondering what (if anything) they can or should do. I suspect its reached a point where neither can, arguably even if they should: they lost the moment of force and the basis of "why" has also become politically charged.
The FTC would only really be driven to act if he imperils US citizens private information or interferes in trade between entities in the public eye, Or if this influences investment decisions to the share value of SpaceX and Tesla assuming there is a public share concern.
The FCC would only be driven by communications law and since Twitter isn't a common carrier or ISP as I understand them and isn't in mobile communications or RF spectrum management spaces, I don't see their role.
He may now have burdens with justice department and warrents to examine logs and data as an ongoing cost of doing business. Not because of what he says but because of the evidentiary status of what Twitter is for other people in the context of the US LEA and justice system.
The EU wants to talk but their legal paths to talk to him about what he is doing to European cultural norms, LEA and related, regulatory, location of data, GDPR whatever else, is pretty complex. And as long as he provides other outcomes like EV for the transition off Gas, and starlink to circumvent ISP monopolies they probably don't want to yank the chain too hard either.