Performance braking
If you are riding a performance bike in the dry and going at a decent speed you have to use the front brake to make use of the braking power available.
If you just/mainly use the back break you'll skid because there isn't any weight transfer to the back wheel when you're braking. If you use the front brake it transfers weight through the forks and onto the front tyre increasing its contact patch and pressing it into the road. I've been riding (mostly performance bikes) for 15+ years and could point to other evidence to support this (e.g. bigger twin brake disks and more powerful calipers on the front).
Just watch Rossi, Stoner and Co in MotoGP. When you see them braking for a corner you will see their forks compress and the back tyre occassionally leaving the tarmac.
I always thought the reason for using the back brake when you're nearly stationary was because it's less likely to unbalance you when the gyroscopic effect of the wheels aren't in play. The rear brake doesn't cause front fork compression which might unbalance you.
Anyway, that's an aside (the whole thing about him noticing his missing leg when he stops). If the story is true how did he not notice when he had to pick his bike up to ride off in the first place? (he might even have had to hop over to it if he was thrown off inthe accident).