A ninth grader is definately old enought to know that you don't ask a question like that.
It's extremely rude and disrespectful. If it were a woman that he asked that question, he would have been expelled from the school.
I find it hard to believe he didn't ask such a question to be intentionally disruptive and disrespectful.
The fact that the kids father is defending him instead of teaching his kid to be respectful says there are serious problems in that family.
Obviously the kid had been coached by his parents to embarrass a military man.