I think you need to re-read that law yourself. Section 230 holds Internet platforms not liable for illegal or libelous speech because they aren't the publisher of that speech. If you read on it also says explicitly they can't be held accountable for:

"any action voluntarily taken in good faith to restrict access to or availability of material that the provider or user considers to be obscene, lewd, lascivious, filthy, excessively violent, harassing, or otherwise objectionable, whether or not such material is constitutionally protected"

Any Internet platform can moderate to their heart's content, even if it goes beyond the extent demanded by the law. There are no constitutional free speech protections on the Internet. The "publisher/platform" thing is pure horseshit spread by people who cry about "online censorship". Unfortunately that tactic seems to be working.