I’m not aware of having said that the shooter was not responsible.
Then don't use a word if you don't know what it means.
I was responding to your saying this: a bunch of Pollyannas who want to scapegoat this poor kid.
"scapegoat" is defined as "someone punished for the errors of others. A whipping boy."
I.e., this word is saying (and you are thus saying) that the ones truly responsible for the crime are not getting the blame, and someone (MM) who is not responsible is.
I’ve repeatedly said—probably more than a dozen times that the kid bears responsibility for his choices and actions—awesome, terminal responsibility, actually.
But facts don’t seem to bother some folks in their pontificating perceptions and interpretations.