It seems like David is having difficulty relinquishing control. He's compulsively training hard at a time when he should be resting up. This is common behaviour in sub-elite athletes who are about to face their first important, competitive race. They use training to manage anxiety and low self-confidence. Effort is equated with progress, even when the opposite is true. A lack of “doing” something "special", even during the taper, brings doubt to the surface. Tapering for an ultra is about training the mind to trust what you’ve built. True confidence is quiet. The taper isn't a test. But for an ego the size of David's, the need for external validation is constant and outweighs the need for restraint.
Of course, this could also be a form of self-sabotage born from fear of failure, regret and inadequacy. That would explain why David already has a couple of excellent excuses up his sleeve (knee injury, ankle injury) for when he starts to struggle in the race. There's no doubt he's in good shape physically, but this race will be won by whomsoever is the strongest mentally.
As a psychologist and runner I find this gradual descent into madness truly fascinating. However, David needs to be careful, he seems to be forgetting he's a coach first and foremost. It's one thing to experiment on yourself and expose your own body to unreasonable risk, but his irrational training methods appear to be bleeding into his coaching practice. This never ends well for a coach!