But many of his readers travel in economy class. They are hoping that the authorities do not make the shoe-testing more onerous than it already is.
Before publishing vulnerabilities, one need to judge the likely outcomes. Perhaps some people think it would be a good thing if air travellers are subjected to further stupid harassment (and risk of foot infection) at Heathrow, because this would reduce the quantity of pointless tourism and even more pointless business meetings.
But the people who would suffer the worst from a further tightening of shoe-related security would be fashion shoe designers, with carry-on bags stuffed with thousands of pounds worth of glamorous stilettos and supercool trainers. Perhaps Schneier should publish that vulnerability as well, drive shoe design underground, and force fashion victims to wear sensible shoes instead!
There are many strange beliefs and customs associated with shoes, some even stranger than the superstitious security checks currently practised at airports around the world. Not far from Heathrow is St Dunstan's Church in Cranford Park. It was St Dunstan who, according to legend, once nailed a pair of horseshoes to the Devil's feet, and this is thought to explain the use of the horseshoe as a good luck charm.
Modern technology has taken the horseshoe magnet and produced an electromagnetic equivalent. Before we can be permitted to board an aeroplane, our possessions must be purified by contact with magnets, so that we can be sure they are safe of the influence of the devil. (Magnets were first described in an ancient Chinese text called The Book of the Devil Valley Master.)
Makes about as much sense as the normal explanation.
Wikipedia: Horseshoe, St Dunstan
Link: St Dunstan's, Cranford Park