I don't disagree with anything you said. But terrorist violence & sedition are not protected speech. Whether they banned him for the right or wrong reason, he still needs to be banned.
I think this confuses "you" with "we".
You shouldn't accept it if you feel it is unfair, and you should express that if you feel the need to, subject to the rules of whatever platform you use to express it.
But "we" (as in the people of the United States), via the powers of government, have no right under the Constitution to compel (or if you prefer, to "not accept") Twitter to allow him to tweet on their platform.
You missed a pretty pertinent qualifier here, but that was interesting, thanks for sharing.