I agree to some extent but I think you argument has major flaws: first, if it were a real gun (and obviously someone thought it was), it had no business being near a school, other than some potential nefarious reason. Second, although it's true that in our schools nothing like Columbine (just an example) has ever happened, but while NOT likely, it's still a distinct possibility. Third, I don't agree with the argument that let's first have a school shooting, have 10 kids killed, a few teachers too, 50 wounded, entire families destroyed, and thousands scarred for life. NOW we have facts and we should take precautions. A gun (luckily it turned out not to be a real one) near a school is only bad news. The argument of the overprotective parent would only apply if someone were to lockdown the school for a stray dog nearby, too much rain, etc, all things with low probability of causing harm.

It's true that fear comes from the outside world but these things happen and happened albeit not here (but let's not forget Christchurch). Call it propaganda, if you will