I don't believe they're worried about the victims
They're worried about the perpetrators wearing their 'elder's badge.
I believe they need to ask the question to newbies for the following reason:
If the brother answers "Yes I've molested someone." He doesn't become a legal liability for the WT because they will certainly not give him the 'clergy privilege'. If they are in a state that requires reporting all they will say is "Go to the authorities so we won't be obligated to be the ones to report you"
If the newby answers "No" and there is abuse later on when he has the WT's 'clergy privilege' they will be able to say, " We are very concerned about this growing problem in today's society. Before this person received his elder's status he was questionned on the subject and he assured us he had never been involved in abuse. We are as shocked and dismayed as you all are by the recent allegations against this individual. "
I believe the question is not to be asked of former elders in case they answer "Yes, I was". Let's just call it opening up a serious "can of worms". The WT immediately puts itself in a position like the Catholic Church knowing one of it's members was a molester while he served on their 'clergy class' It is now a major problem because they KNOW.