Yeah, it is pretty ridiculous. I'll admit to being more partial to Microsoft (as you said, a fan, not a fanboy), but you'll never catch me making such hypocritical claims.
If a PS3 game outsells the same 360 game in America, or if 360 puts up respectable numbers compared to PS3 in Japan, that's something to talk about. However, the reverse is not true.
Edit: within reason, of course. If a 360 game were to outsell the PS3 version five times over, then you'd have at least somewhat of an argument. However, that hasn't happened, so it's a ridiculous claim.