The point is that you should be able to disable anything that is connected to the planes electrical system, to stop fires and prevent damaged systems causing is

The point is that you should be able to disable anything that is connected to the planes electrical system, to stop fires and prevent damaged systems causing issues with other functional systems (i.e. broken GPS causing electrical surges should be disabled to ensure other controls continue to work). Unless your luggage is plugged in, this is something that ground based security should be assessing the risk of prior to placing it in the plane, followed by the redundant fire suppression systems in the luggage hold as a last resort, this should be fairly under control by the time the plane is in the air.