Having read it... Khan managed to move 35+ feet down on a hall, in the time it took LeeRoy to say a couple more words, while falling down? Even after he pressed the button?

Even I would have to call bullshit on that. With the way Khan later described his injuries, it should have been much harder for him to move - not to mention how quickly he deduced it was a bomb.

So either LeeRoy was falling a lot slower than people generally fall

Or Khan's character just SuperKhanned himself to safety.

Won't even touch the fancy shield that managed to pop up.