But you're claiming that the aggressor is somehow more-responsible than the trigger-man
Yes.
By that logic, I am guilty of suicide.
Legally, no. Suicide isn't a crime. Now if you're referring to the act itself (actus reus,) then again no, you did not shoot yourself.
So we should let all those kids out of prison who shot people after being bullied. Ammiright?
If they were defending themselves against aggression, then sure, why not?
You're moving the goalposts. A 3-year-old-trigger-man is not LEGALLY RESPONSIBLE FOR THEIR ACTIONS.
There's no moving of the goalposts. The State decrees that any person victimized by aggression is not LEGALLY RESPONSIBLE FOR THEIR ACTIONS which effectively end said aggression. This is especially true in cases of affirmative defense. (A notable case on the matter would be the Trayvon Martin and George Zimmerman case.)
If a 20 year-old got into their father's unlocked drawer which contains their firearm and then fatally wounded themself, would that still be considered negligent homicide?
You're still not answering the question. I asked would the state be alleging in the charge that I shot my son, his age notwithstanding?