You can pick: rematch or the game gets cancelled altogether.
The scheme was your pick and they're willing to play.
If you refuse, then I'm fine with just deleting the game and keeping it at that if you prefer. The fact is: you didn't win this game.
I won't deny that him moving on to another clanner after telling you he can't play anymore is lame, but it doesn't change that you didn't win the game.