I've thought about this in the past. Why wouldn't they begin closing accounts they think are troublesome? There is no legal right to a twitter account. Except for public blowback, what would the net result be for twitter?
This would be a loss for Twitter. They need Trump as much (or more) than he needs them.
"We arent censoring you, but our algorithm now treats you as spam."
IMO the US is sitting on a powder keg when it comes to power-sharing between the government and Big Tech. What if Google's board took their ball and went home, shutting everything down and becoming a hedge fund? What Jack Dorsey gets fed up and does the same, or worse, loses his mind and forms a cabal that secretly uses Twitter to sew global conflict?
These extreme scenarios point to an ever-present reality: if things really go South between the US government and Big Tech, it won't be simple submission from the industry, it will be a disaster. The side that can threaten violence wins, but when the other side controls what counts as true, what sort of battle is that?