guard rails are for your safety

Even if it takes the victim a while to recognize it, by the time they realize that old granny or grandpa was acting with sexual motivations, the oldster has already gone far over the line. Stopping predatory behaviors in the adult brain keeps children safe, even if there is no guarantee that they would have been harmed by a few sexually motivated pats on the butt. This is how the law works. They don't just outlaw wrecking, they make it illegal to go over 55mph, even in places where it's pretty safe to go 60mph if you are careful. Just to be on the safe side the law draws the line at thought, even as it will be impossible to prove anything until those thoughts eventually turn into action.