Public domain and interest vs liability laws and allegations

From what I've read online with Yahoo News and NY Times reporting, Twitter allows Trump to tweet freely as a public official because it is important for the world to know what a leader is saying, true, false or otherwise (although not if inciting violence per se.)

That said, the impact of what Trump tweets and is broadcast by QAnon to 80 million followers is not without grounds for lawsuits from others. Here is a quote about Tort Law standards from tne NY Times. ..."Landmark New York Times v. Sullivan decision.