We were not there
Cesarnc has hit the nail on the head, we were not there, we do not know the whole story. Fuel to continue would likely have been the first consideration of the Captain. Let's face it, the Captain elected to return and no doubt evaluate the situation on the ground. Having done so fuel would no longer have been his concern, however something made him refuse to ferry the aircraft "gear down" to Mumbai. Mach .82 max would not have been a concern.