If he knows he's not going to be able to compete well enough to win, and may struggle, why risk it? Having the number one ranking is probably worth quite a bit of money in sponsorships. Why go out there, look bad, miss the cut, and potentially mess up his swing? With an injury, a person may start compensating. It may screw up his swing, and it could snowball. It's sometimes hard for golfers to fix little kinks in their swing, and confidence is everything. Who knows what started David Duvall down the wrong path, but it could have been a little thing to start.
However, from a Anal tourny challenge point of view, I kinda wish he had at least hit his 1st tee shot.
Sounds like there are probably a couple casinos that would have liked that too.
For those that did get their futures bets back from Casinos, I think they are probably glad he didn't tee off.