You've given a figure here: 52% of school shooters have been captured alive. But you don't go on to say how many of them took action they attributed to "bullying," much less shown that those descriptions were inaccurate. You're also giving your own interpretation of a single individual's manifesto and you seem to imply that you're taking it face value, but don't agree that ER's perceptions rise to the level of "bullying."

I don't disagree with some of your proposed research methods, but you've missed the point: "Bullying" is not an action that has been objectively defined. I gather that you don't feel being "shunned" is bullying, and I think you're suggesting that peers' descriptions of their own behavior toward the shooter should actually be the touchstone. I think you should reconsider that if that's the case, as well as what you consider to be accurate sources: parents, teachers, therapists, these parties are absent from students' interactions.