I agree, Darren should make good somehow with the people who bought him in the Calcutta (he did win $4,000 in the tournament, so he won't go home empty), at least pay them back half since he was 50-50 to win the match with Skyler. He owes them something any way you look at it.
Appleton does not owe any Calcutta gamblers any money, any way you look at it. He should apologize to his fans for the unprofessional act of oversleeping a match, of course, but that's about the limit. Being human, he made a human mistake, and that's the end of it. He does not owe any Calcutta gamblers anything.
They guys who bought the Calcutta are gamblers who bet they will make money. If they want insurance to reimburse them when unforeseen human behaviors affect their win-loss ratio, they need to hire Lloyds of London.
I do certainly respect the OP as a veteran gambler, because he is not whining about his gambling loss, nor is he claiming anyone owes him anything. Betting on the uncertain outcome of an event is the very essence of gambling. Living with that uncertain outcome is the very essence of what makes a person a gambler, rather than some sort of a lock artist.
As for monies won, although Appleton's tournament winnings were $4k, his profit was probably about nil, taking into account his tournament (and ongoing) expenses. Using mythical profits to repay rail-side gamblers some money he never owed them in the first place just does not make sense.
The other factor is this - there was no guarantee Appleton would have qualified for the Calcutta even if he had arrived fresh and on time to play his Sunday morning match. Woodward was more than a 50% favorite, if his play since Darren's forfeit is any yardstick. Woodward over Appleton would have meant no Calcutta winnings at all for the gamblers who bought Appleton.
A payback to any rail-side gambler is a real slippery slope. Next thing is what about a payback because the pro missed a makeable shot, or miscued because he failed to chalk up? There are many less-that-professional behaviors a pro can exhibit which directly lead to loss of game or match. Oversleeping is just one of many. Even the OP described taking such behavior into account before he placed his bet on Appleton in the Calcutta.
There is not really much difference between flubbing the wakeup time and flubbing an easy shot. Both are foreseeable events which should not happen to a pro, expecially in a 16-player top-pro tournament with minimum $2k expense to hit their first ball. But such things do happen - review a certain easy side pocket shot missed by SVB in the Mosconi Cup, and check back at all the other forfeitures for late appearance in tournaments over the years.
Misses are not unlikely events at all, and failure to show up on time is not so rare either. An experienced TD like Jay Helfert may have witnessed all sorts of misses - including late appearances - probably as much or more than anyone else on the forum, at least.
The OP might reconsider his take on Calcutta gambling for the future. I would say place your bet on Appleton, believing he would never again oversleep, and would also be extra careful to avoid any other human failures he might anticipate.