D%N said:...in many cases terrorists do not aim necessarily at causing harm but at disrupting normal operating schedules and just plainly causing choas...
Exactly. That's why they're called terrorists. From their point of view, the destruction they cause is incidental to whatever insane goal they have. Someone who causes destruction with no goal behind it is just a psychopath.
And I bet this kid's insane goal was just getting some attention. Why else would he post the threat?
So yeah, the guy needs to go to prison for the protection of society, before he succeeds in shooting up a school. But prison won't fix him. He needs therapy. I hope the Swedish prison system provides it.