He can do whatever he wants on that platform. Equally, can elected officials decide to ban that private platform?

Again, apples and oranges. Private citizens vs government. Musk has no power given to him by someone, the government does, using that power in a way that might be considered abusive/authoritarian might yield (deserved) backlash.

I'm not sure if I'm not getting something. It's a for-profit organization vs a government entity. It's not even remotely similar.