The Moors murderer Ian Brady wrote a fascinating book on violent criminality while in prison. (Iirc it is still available to buy on Amazon).
Much of the book is egotistical, sociopathic nonsense from the broken brain of a twisted child abuser - but he does argue that teenagers who commit horrific crimes are already damaged beyond repair and should be removed from society. Brady was caught tying a boy to a lamppost and torturing him when he was only 10 or 11 years old, and several years in an adolescent rehabilitation centre did nothing to curb his sadism. He was already a rapist-murderer in the making by the time he met Myra Hindley. In his opinion, sadists can never change.
The Tate thrower Jonty Bravery didn't stop at throwing a child off a tall building, either - he raped a fellow inmate, and violently bludgeoned a prison nurse, just months after being jailed.
One of Brianna Ghey's killers was also plotting more attacks while in youth prison. The Manchester arena bomber tried to kill a prison officer recently. The James Bulger killers carried on being child sex offenders. These leopards rarely change their spots.
To target a vulnerable, frail 80 year old is blatantlysociopathic. I'd also agree there was a racial element, and the boy didn't target an Asian boy his own age or even a middle aged woman... he picked a defenseless old man.
I could of course be wrong, but I can't imagine he will become a paragon of the community on release. The fact he tried to 'frame' Mr Kholi with such a blatant, laughable lie points to the kind of arrogant, personality disordered thinking that will likely make it impossible to reform him.