I think you've hit on the nub of the problem, Kesstrel. The boys who perpetrate the assaults are accorded the same "vulnerable" status as the victims. And this is totally arse-about-face.
There comes a point where you have to say "yes, I get what you're saying about exclusion to prison pipeline - but that's for minor offences like graffiti, vandalism, shop-lifting. When you get to the level of committing sexual assaults, that's it - the kid is on the prison trajectory, regardless of what is done by way of attempts to rehabilitate them. It's gone too far. We should be into 'greatest good for the greatest number' territory at this point, and that means reform school/borstal and get the little fuckers out of contact with their victims, and make school as safe as it can be for the victims."
Sex offenders have some of the lowest rates of "turning things round" and the highest rates of re-offending going, and we need to accept that this applies regardless of age. Sadly, when it comes to sex offenders, we are in the business of warehousing them where they can't damage other people, rather than trying to reform them. Because trying to reform them is a lost cause.