Let me explain it, first drop the word weak, replace it with the word vulnerable. Preying on the vulnerable.
My daughter is very intelligent and from about age 9 I taught her how that could be a weakness. Intelligence does not equate to street smarts. An intelligent child is no match for a motivated, focused, savy, street smart adult. The smart kids think they have it under control but they don't know squat. They don't know or understand evil.
An adult with half the IQ can and will outsmart an intelligent child.
The other issue is adults tend to treat children who look like adults as adults. They are not adults. Along with that, parents of these kids often give them too long a leash and way too much freedom to make their own decsions. Hence why they look like an adult in the first place.
Then along comes the molester.