1) Western law was not intend ... nor can it suffice ... to constrain savage Bantu Neoliths.
2) Brains are **never** fully developed ... unchanging ... as modern science documents, but western 17-yo have generally been held to know right-from-wrong.
3)**Universal law of survival**: If a persons actions endanger the common good, then that person may be **put down** no matter what the age, mental state or pander-pal (protected) status. If I am attacked by a pack of 13-yo savages then as possible I will shoot them dead .. a jury of my peers ( old white guys ) will not convict me and declare me innocent and a contributor to civil society.
What you **do** determines how you are treated; teen Bantu gang/wilding behavior commonly practiced by those savages is properly treated with deadly force.
So if he wasn't a kid, why does science confirm that our brains aren't fully developed at that age. And Why does Western law dictate a 17 yo can't make certain decisions on his/her own? It is because you're a kid!