Or it could be somewhere hidden in the bag, in a lining somewhere, etc. Or it could be somewhere else on his person, having left traces on the bag after coming in contact with it.
Right, that's why they do a search. Amd if it's hidden so well you won't find it in a search, it'll be hidden that well tomorrow too - where is the sense in pestering this guy for hours and sending him home to get on a plane tomorrow rather than letting him get on a plane today?
The sad truth is that the terrorists here are us. The primary reason nobody has blown up a plane recently in the US is that nobody is TRYING to blow up a plane in the US. If somebody were seriously trying, they'd have done it already.
