What that means is that people who trip these explosives detectors should be politely treated while it is determined whether or not they actually have explosive

What that means is that people who trip these explosives detectors should be politely treated while it is determined whether or not they actually have explosives, since they are likely not really carrying explosives. But this doesn't mean that scanning for explosives is a bad idea, or that people should just be merrily flagged to go on their way, otherwise what is the point of doing any screening? After all, the vast, vast majority of passengers are just trying to go from point A to point B so each and every single scanning method will generate thousands of false positives every year.