I guess those unconscious pilots also managed to turn off the transponder and all the surveillance systems on the aircraft as well??
Or the same fire that killed all electric to the transponder and all the surveillance systems also manged to either poison the crew, or affected pressurisation as well... Pilots don´t get unconscious without reason. It happened before.
Transponder and surveillance systems don´t mean anything, but unconscious pilots still flying along waypoints or an autopilot still working for hours after an electric fire are the details that should make us think twice about that theory...