I see now. I was under the impression only one engine had failed, not two.
2 hadn't - yet. but can you guarantee that another one won't ? Highly unlikely, but what if ??
Technically there is nothing to guarantee that all four engines won't stop at exactly the same time - why not ? Only statistically is it unlikely. but just in case ......... let's maximise our options. I'm going back. Except when I had an engine failure out of Muscat, and continued to Bahrain, which is at sea level and not surrounded by mountainous terrain at night,and incidentally where the spare engine was.
It would have taken me nearly as long to dump down to landing weight as the continued flight towards my destination, with the added advantage that I was proceeding towards less hostile terrain in case of another failure, and with Dubai, Sharjah, Abu Dhabi and Doha en route, continuing was a better option in that case than returning, and I burned off fuel en route to my final destination as well instead of dumping it, better conditions first, passenger convenience second - have you ever been to Muscat ? and economical benefits came along for the ride.
QED.