They can hide a gun or knife in any number of different places - why are shoes even relevant at this point? It's nonsense.

I can replace 95% of the sole of my shoe with plastic explosives and put a small detonator in my carry-on. There is a 100% chance the plastic explosive will NOT be detected by the x-ray or the screener, and there is probably a 99% chance the detonator won't be either, provided I put 5 minutes of planning into how to disguise it.

Kip is an idiot for many reasons - for me, the most glaring is his insistence that cargo screening is not a significant priority. For that, not only is he an idiot, he should be fired.