Huck - the explosive capabilities of those shoes would have been roughly equivalent to a couple of packets of firecrackers. It would only have done serious damage had it been in a container that would have concentrated and directed the blast.
Put another way: I certainly wouldn't have wanted to wear those shoes, but if I was sitting in the row behind this guy, I would almost certainly not have been injured had they gone off.
The chances of penetrating the fuel tanks and causing an explosion there would have been miniscule.