If you have a problem with minors being treated differently than adults in the criminal justice system I don't know what to tell you.
If we're talking rule of law, then I agree. If we're talking developmentally, then I possibly agree. Some 17 year olds are more mature than some 35 year olds I've met, and are capable of full understanding of their actions.
I don't know whether the shooter in this case was. In any case, rule of law applies, and we have to follow that, like it or not.
I do NOT believe that those posting that they'd go for the death penalty for minors are thinking that the shooter was a victim, or an immature child that didn't know right from wrong. More along the lines of them seeing his age as what saved him from possible consequences of his actions.
Everyone should cool it, I think.