The case you reference did not involve a subpoena but an order under the All Writs Act. Annorder which compelled certain behaviour unless the order was appealed

The case you reference did not involve a subpoena but an order under the All Writs Act. Annorder which compelled certain behaviour unless the order was appealed within a specified time. Apple appealed the order within that time period and thus was in full compliance with the order. The government withdrew the case before the courts could rule whether the order was legal. I assume Apple would have complied with it if it was ruled so. What we do know from this case is that Apple did attempt to assist the FBI with accessing the phone even without a court compelling them to do so.