Anyone who has raised children understands part of their job is protecting children from themselves. They go places they shouldn't and do things that might harm themselves.
It is believed today that judgment and decision making skills are not fully developed until your 20's. How many young adults exhibit risky behavior? Do they know better? Sure but they do it anyway.
So we honestly think an 11 year old is remotely capable of seeing beyond the moment and grasping the consequences?
Even a lot of adults aren't able to see the most basic things such as cheat on your wife and you lose your marriage. Steal from your employer and lose your job.
How many adults are not able to control their anger? And we have years of practice and opportunities to see what happens when we lose our cool.
Just because this boy understands the basics or "right" and "wrong" such as killing is wrong, doesn't mean he is able to inact it at all times. How many of us has lost our temper and broke something important or said something that caused serious damage to our relationships?
How often have we as adults made mistakes we knew better than to do but did it anyway?
An 11 year old is considerably less mature than any of us.
But some mistakes last a lifetime.