Heh. Yeah, it does seem odd that he keeps winning with the exact same moves ( 1.e3 f6 2.d4 g5 3.Qh5# ) over and over. (What is that tricky opening they keep playing, anyway, the Kavorkian Defense, Pufferfish Variation??)
At the same time, I'm not sure who this kind of 'cheating' hurts, other than the poor soul who does it. I mean, are the ratings for the game, or the game for the ratings? If like most people the game is what's important to you, then at worst what this person is doing is making themself look like they could take you in a game, when most likely they haven't a prayer. So challenge them. Hey, free rating points, right?