"During the Singapore incident, the number 1 engine operated normally. It just would not shut down after they arrived
Correct
Engine shut down/fuel cut off is a not connected to the Fadec.
It takes a powered command to shut down the engine ie close the fuel valve. It appears that wire or wire bundle that controls the fuel shut off valve was damaged or in some way unpowered. Not an issue just ask the AA guys that tried to do a USA continental flight on 30 min battery power in a 57. They made it from SEA to ORD but landed safely but could not shut down the engines. You do not want to shut down an engine for disruption of electrical power, lightning stike, switching busses, the list is pretty endless.
The thrust/throttle control in non linkage/non cable control or Fadec type applications actually generates its own power and is routed to the throttle controls and back to the engine to give thrust control. Thrust control is a seperate system and does not shut down the engine. It appears this cable bundle was unaffected.
VFD