Despite all the discussion, the 777-200ER remains allowable to land at maximum takeoff weight and if set down at 360 fr/min or less, specifies a 4 hour overweight inspection. This can change if there is an icy runway and that was not the case. It still should stop in 6,000 feet and they had 12,000 feet. Did they dump because one ATC gave them a shorter runway and they realized that without their runway selected runway stopping was going to be a problem? Turning back with a plan suddenly altered by an ATC refusing the runway requested causing immediate action? ATC error resulting in crew overload and with time to land on a suddenly shorter runway created cockpit caos?