On a positive note: since they didn't shut down the engine in flight, this incident does not negatively affect the IFSD rate and ETOPS rating of this airframe/engine.
Probably closer to the truth than you might think. I've know this to happen with other 777 operators that have flown an engine at idle for several hours to destination. Not shutting it down means you don't have to Land at nearest suitable airport and it doesn't count as an IFSD affecting ETOP's.
This should not be part of the discussion about this incident as IFSD numbers are just that and meaningless as single incidents.
The FAA will be all over this event when the details are known