It surprises me that it is possible for capsaicin to kill someone. Maybe it is something else or a combination of things but I await further evidence.
I do like to eat spicy but I top out somewhere around habaneros. It would be good to know if the peppers might kill me. I already think I'm pretty careful with them, but I'll be more so if there's real danger.
Unfortunate for this kid. Best wishes to his family.