Objective morality as a proper basic belief

[The Grand Nudger]

Right, but you have just illustrated that harm is not the measurement in the three scenarios.

No..I haven't.  We call one killer a hero because, ostensibly, his killing has prevented some greater harm.  We call another a monster because his killing -is- the harm, and we call the last unfit because he is incapable of understanding or intending, or preventing himself from harm.

I'd call this an epic fail, but in context of your failure in literally every aspect of this discussion it rates no more than a meh.

It was an underlying set of values that say that say humans have value, individually, they have intrinsic rights not to be killed, that these rights can be superseded in certain circumstances, and accountability requires an understanding of these underlying values.

You mean a modifying set of logical principles that is applied to the axiom of harm. 

Regarding this last example, someone unfit to be held accountable might be a person that knew very well that killing would create harm (resulting in a dead guy), but did not have a firm grasp on the underlying value framework to make sense of it.

Right, so we withhold some measure of condemnation.  The act was still harmful, it was still immoral, he simply isn't fit for the punishment that such an act would otherwise deserve.  He gets the padded cell rather than the electric chair. Amusingly, this is why I give -you- a pass on morality as well. Your comments and moral beliefs would be evil, if it weren't for your inability to understand the subject matter.