We are supposed to excuse the rampage because he was a victim of or witness to Serbian violence ?
How many refugees has the US taken in who've experienced far worse than this kid and who never would have contemplated that kind of madness?
I'm not exactly sympathetic.
I don't know how easily we can rank the trauma of massacres (if he was a targeted victim, which I don't believe is ever directly proposed) but your point cuts to the heart of the matter and is, of course, correct.