For a mentally capable adult, perhaps. We have plenty of research to show that the brains of juveniles are wired differently. That doesn't mean no punishment, but it means that a life sentence is excessive and rehabilitation should be tried.
A childs reasoning would more likely follow this kind of path: Child wants alcohol->storekeeper has alcohol->child capable of coercion by force (ie stabbing)—>child gets alcohol from storekeeper
However, instead he did this: Young man wants alcohol->storekeeper has alcohol—>alcohol costs money that young man does not have—>innocent passerby’s have money—> young man capable of coercion by force (ie stabbing)—>young man stabs innocent passerby’s for their money—>Evaluate whether amount stolen is enough for alcohol, if not, repeat previous steps, if so—->young man gets alcohol from storekeeper
Good decisions are not proof of brain development, however complex ones are. Given the evidence I would say he was rightly judged as an adult.
Life without parole seems like it should be reserved for those who are beyond saving. Not sure a 15 year old boy would classify as such. It all depends on your view of retribution vs rehabilitation though.
Maybe you don’t think he deserves his punishment. I certainly do. The type of person who would go on a stabbing spree for wine money is not the kind of person who has any place in society I want to live.
Intentionally misconstruing what others say is something best left for Reddit.