Might does not make right
jeez lol only the 4th time
You cannot deny he has the right to do whatever he wants on his server. You can say might doesn't make right, whatever. It might be wrong for him to do it, but he still can. This is something you can't deny.
Anyone has the right to do anything on their own server. Even if it's unfair or wrong it's their server, it's not your right as a player to be able to play in their exactly how you want. They can ban you from it whenever they want.
Now, should they? Is it right? No, they shouldn't, and it's not right. Like everyone likes to repeat ten million loving times as if every single person on forums hasn't already read the quote "Might doesn't make right". Are they idiots or handicaps for doing it? That's all a matter of opinion. If you are an idiot like this and ban people randomly, then no one will come to your server. Or will want to, anyways. But that doesn't mean you can't.