Earlier quoted context omitted.
That arguably changes when the President starts to use it as a primary means of communication with the citizenry.
They didn't remove his message. They merely pointed out it was misinforming the public. Speaking of which, shouldn't we make it a crime to lie or substantially mislead the public while holding public office?
But I also think that the more Twitter is used to disintermediate political communication, the more it starts to look like a vital public utility. It's tough to say where the line will or should be drawn. I don't envy Jack Dorsey's position, that's for sure.
As far as making a law that prohibits politicians from lying to the public, I don't see a way to write a law like that without making the situation even worse.