The Mormons have a culture of anthropological scholarship, a byproduct of their missionary programme and (to a lesser extent) of disproportionately many Mormons working as intelligence analysts. As such, it’s not implausible that they might see through such a ruse.
It may do the Amish well to start quietly hoarding supercapacitors as soon as Amish-Mormon relations start souring. Or even before: one could make a case for a preprepared EMP bomb being the Amish equivalent of a nuclear deterrent against any potential aggressors.