Well if its a four engine aircraft , rules don't require it to "land at the nearest suitable airport" With 3 engines turning, FL270 that would probalbly be the 3 engine altitude. at the weights SIA generally would be at on a flight from Europe to the middle east. or vice versa. However if it was one of SIA's B777 then you would probably expect them diverting into one their enroute alternates
The terrain over Iran and Turkey is not as high as over Pakistan enroute to China and Twin engines as well as 4 engines regularly fly across. Engine out are not a problem as much as a rapid depressurization. To optimize their routes airlines have "escape routes" that allow them to use lower altitudes (14000/10000')where Grid Moras and MORA are higher
BM