I recall, if gear box low pressure red light illuminates, feather and shut down that engine asap to preserve the gear box. Not saying this has anything to do with this incident, .........but?
That is the accessory gearbox further back on the engine not the reduction gearbox.
The reason for the procedure was that accessory gearbox was not covered by the fire extinguishers and low px would sometimes end in a fire. They did provide it with a fire detection system though!