If it is a question of unpaid royalties, I wonder how much money we are talking about. If the amount is "reasonable", I would, if I were Mark, have just paid the money to David and made peace, or at least tried to offer a reasonable compensation in case the amount was very large. This of course would mean that Mark had been in the wrong all along, and I think he's the kind of guy who'd never admit to that. Too proud. Plus if that kind of information surfaced, it would seriously mar Mark's public image.