It's not a publicly traded company and hence Musk + his backers can do whatever they want. It's their toy and I'm not in the business of policing anything (within the law) they do with it.

It would be irksome if Musk went on lawsuit spree + PR campaign incessantly complaining that advertisers are 'killing free speech' by not advertising on the platform. Like some weird civic duty that publicly traded businesses with a fiduciary directive ought to have. But, let's be real, folks operating on Musk's level are too clever/business-savvy for anything that amateurish.