buaaahahah. are you kidding? You have a serious problem man. Before I thought there was some merit to you correcting people. But now I know you just annoy people for fun.
You could possibly believe that using light 220 grade sand paper to make paint adhere to the surface better could even come close to compromising the integrity of the shell. Giro says not to use paint so they can sell more helmets, buddy. The "poor, unsuspecting kid" part made me laugh out loud. Actually, the helmet has a bomb in one of the earpads! The unsuspecting kid has no idea what is about it hit him! hahaha.
Oh yeah, and lastly: how many Giro Nines have been sent back for warrenty? haha, you are pretty absurd.