Mad (Flt) Scientist,
When a SB is issued by the manufacturer, it must go to someone in the company to decide the priority, in my company that was the Type Engineer. When reading it and it is presumed that they understand the aircraft systems, the person must have wondered why it was issued and the implication that there was a possibility that the spar valves wouldn't be closed when the fire handles are pulled. I would have also thought that the training course for the electrics on the 777 would have shown up the anomaly. Hindsight I know, but having been a TE I know how important it is to realise the implications of SB's etc on Operations.