It's basically because you won, and he probably looked for wins in his server so he kicked you. Basically in reverse it would be you leaving the server right before he won

Perhaps he didnt kick you at all. Instead, your server crashed and both of you were disconnected. That might be the reason he was not in the room afterwards either. Did you see the message saying you were kicked?

If no one was there then thats what probably happened.

Even if he did kick you, you were either doing something wrong or he just didn't like Blackbelts- in his server.

And whoever said "If you were a blackbelt would you do the same" no i wouldn't.

It's just a win/lose who cares.