reading all the pages in this thread and the question was forming in the back of my mind early, had to read to the ninth page before someone beat me to it.
Unless the authorities have recently relaxed the minimum system requirements for entering ETOPS areas, my many years of plowing twin Boeings and Airbuses across oceans left me with the distinct memory that the relevant QRH page left no doubt: three functioning hydraulic systems required to fly beyond sixty minutes of an adequate airport.
Maybe the references to it failing half an hour or an hour after departure are incorrect and the sole mention of it happening four hours out is correct.
If it failed subsequent to ETOPS entry then continuing became an option.
Nice landing, nonetheless...