I just played a game where I was about to eliminate a player and take four cards, which would have given me a significant advantage. I was attacking the guy's last territory with seconds left, and just then the other remaining player sent me an attack request.
There were only three of us left, so it was bleeding obvious who he wanted me to attack, It also slowed me down just enough to allow time to run out just as I was rolling the dice.
Ultimate dick move. Attack requests should be disabled in Non-ally games anyway, but you shouldn't be allowed to send one to a player in the middle of his turn. It's like shouting at a guy during the middle of his golf swing.