Most persons 13 and up will respond to a violent assault the same way an adult will. Start yelling, call 911, tell your parents, etc.
Not all children mature at the same age. Some 13-14 year-old children have the maturity level of a 10 year-old, and vice versa. Therefore, predators who are looking to molest young teens will look for ones who are more vulnerable for whatever reason. Also, not all predators force themselves upon their victims. As I'm sure you know, they often convince the children to consent. There is a reason that society sees fit to punish teachers who have sex with 15-16 year old students, who in most cases are mature enough to be able to "resist."
As for your statement that this is irrelevant, it's only relevant because you claimed that JWs don't assign minors to work with members of the congregation besides their parents and then claimed that 13-year old children are not minors.(!) There are plenty of vulnerable JW youths out there and even if the kid is older than 13 it seems like it should go without saying that if the elders know someone is an abuser, he should not ever be exposed alone to a child.