I don't see how they have a choice. If they decide to exercise editorial control then they might be considered in the content creation business by virtue of exercising editorial control and forfeit immunity under Section 230 of the Communications Decency Act. If Facebook had to be liable for what was published on their system they would be facing the possibility of liability judgements many times their market cap.
Link: https://technology.findlaw.com/modern-law-practice/understan...