People advocating that position usually have a very specific idea about how they want sites to be moderated, but section 230 is about not treating platforms as if they're the speaker when one of their users posts illegal speech, regardless of moderation. Of course, politically biased speech is not illegal, so it's really about punishing platforms for moderation somebody doesn't like.

A more reasonable target for a 230 carve-out would be recommendation algorithms. Those aren't merely passively hosting user-generated content, but actively selecting what they think you should see to keep you engaged with the platform. Featuring content rather than showing it ordered by some simple criterion like time should be treated as editorializing rather than moderation. If a human editor decides to feature lies I tweet about you on their "best tweets of the week" page, you may be able to sue them for libel. If twitter's algorithm shows lies I tweet about you to a large audience, you currently can't.