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.
It's true that terrorism & sedition is not protected speech, but it's also true that the logic Twitter is invoking here to connect the tweets to terrorism & sedition is questionable at best. Regardless, why should we accept Twitter banning people for the "wrong" reasons?
> why should we accept Twitter banning people for the "wrong" reasons
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.