There's a lot more to it than hatching out evil, though. When children do something that evil, it points to a situation that's lead the kid's brain to breaking in that way, and should be treated differently than a fully developed, reasonable adult. We don't allow kids to sign contracts, or drive, or serve in the military. Their brains just aren't done baking.
One of the boys has done well for himself since being released. I think that when rehabilitation works, we should let it. Growing up in custody, even if it's an improvement from the home you were born in, is still being deprived of the freedoms and privileges of other children, which might be punitive enough for kids who commit crime.
Don't get me wrong, I'm not applauding them or anything. It was awful, and I think the pedo should've lost his new identity the second he started running his mouth about it, let alone when he started offending again- I think both of them should be popped into the clink or a mental institution the second they reoffend, and it's disgusting that one of them has remained free and protected.
I also think they should've been given to the custody of an institution that could deal with young offenders who have committed so severe a crime, not the understaffed, grim place they ended up in.