Not a lawyer, but I find it highly improbably that section 230 would shield them in this case. It's trivial to think of a scenario where the removal of information constitutes the production of a message, and in that scenario, the information is not itself produced by third parties using a platform, but by the platform itself.

Like, if I write a note that reads: "The President of the United States should morn those that die of COVID." And the note is posted by someone else with "morn those that" removed, they can no longer point to me as the producer of the message. Likewise if video footage is edited to show a different story than reality, the person that did the editing is culpable for the resulting hoax, not the videographer. I think the same applies to editing information produced by multiple other people. The moment you edit information to conform to a certain narrative, you are then the source of that new narrative. In that way, I think Facebook, though they were editing the information available on their platform, are in fact the source of a new narrative that exists in the negative space of their editing.

It would indeed be super interesting to see this argued in court. It would make a really good balance to the free reign that platforms have now to curtail certain messages or information. If they were responsible for the story the surviving information creates, it would make them tread more carefully when censoring users.