It may not work 100% of the time, but what if it works 90% or 95%? Come back with some meaningful data that includes thousands of kids.
That's closely related to something I've commented on in other threads. How many such threats to shoot up a school, or shoot the president, or phony bomb threats, is law enforcement dealing with in any give time frame?
Was LEF in that Florida area dealing with three or four, thirty or forty, three or four hundred, or a thousand or more threats to commit serious crimes during the past year?
I don't know the answer, but it is very relevant to how thoroughly each threatened crime can be investigated and dealt with.
All the more reason to punish the pranksters and hot heads to discourage that sort and eliminate as many low probability threats as possible.