IMO the bus was taken down to de-power the left FMS which would allow direct pilot control of the aircraft without interference from the FMS.
Surely there are easier ways to take 'direct pilot control of the aircraft without interference from the FMS'. Why not just use other autopilot modes such as HDG or TRK? Failing that, why not just disconnect the autopilot and fly manually? Far easier than taking down half the aircraft's electrics.
There is no other way to disable the satellite transmitter/modem from the flight deck other than to de-power the left AC Bus. The CB's for this are in the EE Bay.
I beg to disagree. The CBs for the satcom may be in the EE bay (I can't remember to be honest), but on the 777s I flew there was definitely a way for the flight crew to force the system to log-off.