But his END was what? 400' or so ft?
I doubt it, what would be the point in Helium then.
I'm sure you know you can tailor helium to any END you want, from 4 percent Oxygen to 40 percent Oxygen. I'm only guessing, but considering his knowledge and financial backing, i'm certain he wasn't skimping. With 27 Bottles of gas on that dive, I'm pretty sure he was diving several mixes of HE. It would be stupid to have an END of 400' when you can have any END you want at any depth.