Jessie, haven't got the schematic any more so I'm just talking off the top of my head, but:
Selecting emergency fuel bypasses the main metering valve and allows the throttle to directly control how much fuel gets to the engine for combustion, but does it also isolate the bleed band control system? That would be the key. We need to know what controls the bleed band.
Even though N1 speed is now being controlled by the throttle, possibly the fuel pressure in the FCU (whatever it's doing, the engine doesn't really care about the automatic side now) is still signalling the bleed band to operate, and the position of the N2 lever may have some effect on that.
I'd also be interested to hear any further info, for old time's sake!