I didnt miss your point at all. You want to believe somehow that the metal detector is a magical panacea which will stop deranged nutjobs and thus justifies the complete disregard for the rights of everyone else.
Meanwhile, back in the real world, I defy you to show me a single example of a metal detector actually stopping a crime.
To someone determined to do something like what you suggest, the metal detector is a lock on a screen door. Makes those who dont think feel better, but has no real effect on the outcome.
Ok. I was taking an extreme example and not suggesting that metal detectors are a cure all. I do think they are necessary in light of the society we have today. On that note, what would you do if you were placed in charge of security of a school since you are against metal detectors.