What’s always interesting is that in the beginning of any group, there is no hazing. Then after a while, you have some idiots who dream basic hazing 101. After a couple of years, you advance to hazing 201. And then finally, you get into bondage hazing. None of the old guys in the very beginning can understand how things got so screwed up.
They're probably afraid that having their sons questioned will be very distressing for the boys, but fortunately I believe this is actually a crime that can be pursued automatically. They may also be afraid of retribution from the jocks or their parents, because in a lot of these places, no matter what the jocks do, it's cool.
That said, I think this goes way beyond hazing, and the older students should be charged with sexual assault, along with the adults who set them up to it.