There were few people who worked in spaceX and they said some bad things on how Elon was runing the company and said that the board or whoever needs to find a way to keep Elon not doing some silly stuff to interrupt the billions of dollars in research, and what did Elon do in response? He fired those people and made sure that he was running a company where nobody could speak against him like that.

If anyone truly believes that Elon will have a twitter that will be "free speech" I am sorry but you are mislead, it will be a place with lies, and it will be lies that benefits him or things he likes, and the "free speech" he is talking about is basically "saying whatever wrong fact as long as I want to, and nobody can stop me now and I can manipulate the markets this way as well!" that is all he is trying to do and nothing more.