Trolling categorised as "obscene" would be removable, but otherwise may be protected by the First Amendment. Also, the fact that every content moderation decision may be subject to litigation would make it extremely difficult for the government to meaningfully moderate content.
Private platforms, not bound by the First Amendment, and allowed to moderate without assuming liability by Section 230, wouldn't suffer these problems
[1]: Via White Buffalo v. UT Austin
In a similar vein with the fact that it's illegal to yell out "FIRE!" in a crowded theater unless there is actually a fire, they could make it illegal to advertise private businesses and make posters directly legally responsible for what they post.
If this does come about though, I hope they prohibit businesses and "Media Groups" or whatever from creating accounts or at least lock them into a walled garden that you have to voluntarily enter, segregating them from the general populace.