I met the guy once, so I can't speak for him, but having read his stuff and followed him on his website, and now on Facebook and Discovery, he has been barefoot for years and has built up a very thick pad of callused skin on his feet. I have also seen this with pacific islanders.

In fact I would guess with the additional thickening and toughening of the bottom of his feet that it would be quite uncomfortable to where normal footwear.

My 2 cents.