I'm not sure what you mean by banned or censorship, but Twitter isn't the government and I'm not sure how this example is "anti-democratic authoritarianism". Seems like they should be allowed to ban people from their platform who violate the terms of service. There are tons of platform/content providers that don't allow specific types of content even though it is legal.
If people disagree with Twitter they can leave the platform for another one or shareholders can act and have the firm change course. Trump still daily says whatever he wants on other platforms without the government censoring him.
If people disagree with Twitter they can leave the platform for another one or shareholders can act and have the firm change course. Trump still daily says whatever he wants on other platforms without the government censoring him.