The very inaction of the SEC or FTC and so on of defending free speech when a company’s privilege of using public trading is exactly the problem, before public most Social Media companies were cool, in fact it was after public trading that they went dark.
Maybe a lot of rich kids investing trust funds in big tech. China also gets in on it no doubt. They do in gaming.
So if your looking for laws that permit the abridging and denial of free speech of “muh private companies” then look no further than the Securities Regulations and Laws, they allow it. They won’t pull anything out of the stock market, and therefore this inaction is state censorship.
Failing to do is as bad as doing, in the case of violating natural rights.

Recommend using Dissenter and Gabtrends to make comments, just @TheBlackJester if you want me to notice it. It’s better than the native one.