Shadowbanning people means banning people, it's obviously separate from moderation of individual tweets. AFAIK the only subreddit that has banned me was the_donald, but I can obviously have my content removed if I post to a news subreddit from domains they consider unacceptable.

It is honestly silly to be surprised. Any community with just a few thousand users will ban entire domains, it's not surprising that they resort to banning entire TLDs at the billion user level.