tough to prove at 13.
True -- which is really the only place where the prosecutor really had discretion. Had they been a year or two older, and I'd want 'em in chains for a while.
The boys' age could be a mitigating factor, on the claim that they're sexually immature and unaware of what they were doing. At 13, though, especially nowadays, I think that's getting to be a pretty flimsy defense.
Regardless, what they did is still a serious offense. At the very least, they need to be removed from that school.