I think Trump would be on solid ground if he were to argue that Twitter's incredibly stupid decision to append "fact-checks" to his tweets does constitute traditional "publisher" activity, and therefore deprives Twitter of Section 230 protections https://www.reuters.com/article/us-twitter-trump-executive-order-social-idUSKBN2340MW

However, it would be going way too far if they were to also claim that Twitter now has liability for individual tweets -- i.e. "publications" that Twitter itself had no role in crafting. Need to be careful drawing distinctions here

Of course, in practical terms Trump almost certainly won't be doing anything to actually effect a policy change here. It's just a political statement. Still worth getting the logic right for posterity https://twitter.com/matthewstoller/status/1265998181881597955