I don't know if Durant has written a book but something tells me he has. If he addressed the issue in a book (I'm not saying he has) why not address it before people who could be in the military in a few short months or years. It's nothing they don't already know about anyway. It's as another poster addressed, they need to know the truth about what the civilized world is up against.
There could be things we don't know about what was going on at the time. If the young people weren't taking his remarks seriously - joking around, etc. - I would probably sidestepped the question too.
You seem to be relying upon the assumption that Durant has addressed the issue of being raped ina book that he either has written, or is in the process of writing. If addressing the subject in a book would make the question fair game, then if Durant wrote a book and did not mention rape, would that then make the question inappropriate?
We're just going to have to respectfully disagree here. I don't believe that the child wanted to know so that he could make a decision about going into the military. Personal experience has taught me that such questions, asked in such a way, are a function of morbid curiosity, and fixation with the macabre, and nothing else.
Yes he did write a book: "In the Company of Heroes: A True Story." Here's the link to it on Amazon: