So what?

Let's take aside the charged component of this and just suppose hypothetically that 100% of the assaulting students belonged to some subgroup. So what?

They may be 100% black, or 100% male, or something, but it's not like you can reasonably just say "So no males at our school." Regardless of whether you can find a subgroup who this belongs to with a very low specificity, you still need policies that tackle the behavior itself rather than trying to find some really weak predictor.