Opinions on ethics of this PBW move

[tesco samoa]

I had that happen in a pbem game. I was beating a human player and he surrendered to a computer player. I was pissed and told him that it was crap. Since he was not even at war with the computer player. It is a spiteful move. I asked the guy why he did that and the resonse was that it would make the computer harder. So I informed the player that that was the Last PBEM game he plays with me until he cuts that crap out. Hey 100 hours invested into a game.... and it is one of the unwritten rules of any stag. pbem game. Always surrender to those that attack you. If you wish to play another game.