What kind of regulation is it subjected to? It doesn't have to be neutral, and it has a legally-tested right to lie, and mislead. And that's for first-party content directly produced by it.
You can read the order. Section 230 of the Communication Decency Act set out provisions protecting internet service providers from liability for obscene, lewd, etc content on the basis they are a neutral platform (like an email provider) and not an active arbiter and curator of content published on their page. The law clearly states it's protection for private blocking and screening of offensive material (lewd, lascivious, filthy, excessive violent, harassing, etc). Not for editorial protection. Not for arbitrary enforcement of TOS.
Looking forward to an army of bureaucrats making sure every tweet is kosher, then? An agency will last longer, with staff that lasts longer, than any single presidency.
Sounds like a nightmare scenario for an "un-PC" asshole like Trump.
I really don't think you, or Trump, understand the ramifications of what you're asking for. You have this ideal, naive view of what's allowed in "public squares" that doesn't seem to match what happens.
See: Trumps belief he was persecuted by other government agencies. Which he complains about on Twitter. Which would now be answering to a... government agency...
And then, once that happens, now you have no recourse - even if you build another platform, it ends up controlled by the same regulators.