Again, it's all in the eye of the beholder. To you 6000 rounds is a lot of ammo. To the media, it's an armory. To me, that's about how many rounds I shoot in year.
Bro this is not normal behavior wearing shirts that says he kills, telling people he will kill everyone, and having an obsession with guns and shit, this is precisely the behaviour of a psychopath that could very well be a killers. All the signs are there, this is exactly how people behave that do these mass murders, so no I wouldn't take all this lightly if I was the authorities, in fact i would lock him up and throw away the key