Does that mean we can sue Fox entertainment fake news network?
If someone tweets that you are a murderer, you can't sue Twitter (or rather, if you do, Twitter will be protected by Section 230).
However, suppose Twitter announces the following policy: "Any tweet which calls someone a murderer, shall be deleted, unless the alleged murderer is gulli1010". Should you be allowed to sue Twitter then? That's a more nuanced question. And what if the above policy isn't an official policy but is a de facto policy?