Originally Posted by Repetitive Monkey

When a 13 year old boy gets laid by an adult, men see it from the boy's perspective - getting laid by a hot chick - and as such don't have a negative response to it. If the adult is the male and the kid is the female however, men see it from the adult's perspective - getting a kid to bed - and are repulsed by this attraction to little kids. In addition, it is common knowledge that no normal 13 year old boy will take mental or otherwise damage by having sex with a hot chick. On the contrary, he will benefit from it and have increased confidence and happiness.

So I wouldn't say that the GFY reaction to these cases is so much hypocritical as it is naturally and harmlessly biased.