I see it as a futures contract on the value of the BTC. Selling a mining ASIC locks in profit for the seller, betting that this will exceed the time-value generated from the rig itself. Buying a rig locks in a loss, betting that it will pay for itself. We can't be certain whether the BTC will be at US$1,000 or US$1 a year from now. You could make a case for either side, that's why the contract exists.
Which, by the way, doesn't mean they are betting against BTC. They just elected to take sure profit up front, over less certain profit of potentially greater value long-term.