I don’t think Twitter is wrong, and it is not really different from Apple not letting pornography into the App Store, but it is still deeply troubling to me at some level. And it is neither moderation like discussed in the article or censorship as discussed in the article.
And that's the precise point at which they cease to be a "middleman" and become a publisher.
Nobody argues that owners of physical premises should choose between accepting full responsibility for every action on their premises or being utterly powerless to eject any person for any reason.
I'll take your word for it that none of your opinions or ideas were controversial enough to upset your publisher, but do you feel the editorial process would have been completely uninterested in removing opinions or other ideas before publication if your draft contained frequent asides praising the Third Reich or suggesting that the practice of software development would be greatly improved by only allowing men to participate in it?