Dang, that sucks. :(
Wonder if he had sunglasses on and/or a new pair where the bottom of 'em made it hard to see where the stage ended. I had a pair of sunglasses one time that had a bunch of blind spots. Threw them away.
Hope he recovers quickly.
Why the hell don't they put some kind of padding in that area jic someone falls and/or put a tape/paint line about two feet before the edge so you can see it.