You're making a false equivalence between the left and the right on this topic.
The left has said that moderating online communities is legal because of the First Amendment. They're private companies. The right then called for an end to the First Amendment as we've known it by banning private companies from moderating their platforms.
There has been no such call from the left. The left (and this thread) laments what Elon is doing, but no one is saying he's breaking a law or that he should be breaking a law. No one is calling for the government to step in.