You're right, OP should have no reasonable expectation that he'd actually receive benefits traditionally conferred on a Platinum after completing a "Platinum challenge". In fact, it would be perfectly acceptable for DL to not offer upgrades or award redeposits to those who have earned status via a challenge if they bury that in the shrink ray text as well. Just send them a Platinum luggage tag and tell them to shut up and like it. Seems like a great way to poach potential HVCs from your competitors, and makes a great first impression.