Anything with a very low rate of true positives applied to a large population is going to have an insane false positive rate. EG a 1 in 7M issue applied to 70M students with a 1% false positive rate would produce 700k false positives. Worse people who are actually planning a school shooting may be more likely to avoid telegraphing their intentions. So you could damage 700k kids futures and traumatize them without even catching many or any of the killers.