a number of the policies out there in the US do not itemize how the aircraft is maintained or operated
Of course they don't. An insurer is an expert in risk but not in the specific operation nor the maintenance of an aeroplane. The national aviation bodies do that and they provide the expertise and rules that the insurer relies on. It is simple to say the insurer will always require that the flight is conducted fully in accordance with the law and regulation. There are circumstances requiring aircraft type training and supervision that history has shown will reduce the insurers risk before the PIC will be given cover.
There will always be the exceptional circumstances that require specific permissions and oversite. The FAA in this instance have a protocol in place to deal with such applications. An application for the stunt was made to the FAA but was rejected. No underwriter will ever consider insuring a flight that is to be intentionally conducted illegally.