Earlier quoted context omitted.
Okay. But when Twitter or whoever takes your post down, how does treating them "as a publisher" help you? It doesn't. They have a 1st Amendment right to do that.
Why wasn’t Stratton Oakmont v Prodigy Services overturned on 1A grounds? “... if they are neutral platforms, they should have immunity from litigation. If they are publishers making editorial choices, then they should relinquish this valuable exemption. They can’t claim that Section 230 immunity is necessary to protect free speech, while they shape, control, and censor the speech on their platforms. Either the courts…
That would still be a problem (because it would allow companies to censor critics, even if the criticism wasn't actually defamatory), but at least we wouldn't have incoherent arguments about a non-existent publisher/platform dichotomy.
That city-journal piece is pretty awful. For instance, regarding the bit you quoted, they absolutely can claim that 230 protects free speech. Private censorship on private property is free speech.
Congress almost certainly can't pass a law that outlaws viewpoint discrimination for web sites that would survive 1A scrutiny. Fiddling with defamation liability to get around the constitution might work, but just because you can doesn't mean you should.