I agree with you that as long it is there, I am enforcing any GFCI rule. That is the most important innovation to save lives in the history of electricity.
I am always arguing with people about refrigerators and sump pumps that trip GFCIs. They are broken and should be repaired or retired, not bootlegged on a non-GFCI circuit.
Put one of those old style 2 prong adapters on the plug, ground the pigtail and loop it through a current probe on a scope, fight is over. On a sump pump, your clamp works to make your point. On a fridge, A/C or whatever, you are seeing the electrical representation of a thunderstorm inside that compressor.
Then I ask, "wanna unhook that ground and hold the pigtail"?
Still no takers.
