Earlier quoted context omitted.
What else do you do with someone who is relentlessly rude?
It's not that it's wrong (I wouldn't know, I haven't seen any evidence of rudeness, and the description of rudeness in the email seems really weak), it's that it assumes an unwarranted and overreaching position of authority.
What authority?
They can’t force him to not talk to anyone or not Tweet at anyone. He can do whatever he wants.
They’re just saying he’s not welcome in their community if he does. It’s their club so their rules.