Like a lot of things in the fast, fast information age, what we knew on the day of the event, and what ACTUALLY happened are very different. Not completely so, but largely so. And seemingly shockingly, a lot of it had to do with the NATURE of the kids, not whether they listened to such and such band, or were bullied. One a seeming psychopath and one a lonely kid who wanted to fit in.
I did hear the author on NPR the morning of the April 20th, so I heard from his perspective what the media got wrong, and HOW they got it wrong. It was this sort of feedback loop where they (the media) heard a rumor and sort of insinuated the rumor was true to the kids, who would then recycle it to the next report; rinse recycle, repeat. Thankfully, the two kids could not wire bombs particularly well, and got bored in one area and would sort of blow things up (with no people around) for entertainment purposes, otherwise the damage done would have been a LOT worse.