but they are all circumstantial incidents
Just because they are alleged "circumstantial incidents", does not mean that they have not occurred with a particular combination of aircraft type, seat position, PED type, PED activity, avionics make, etc, that has not been replicated by the alleged studies.
How can an aircraft manufacturer, CASA, the FAA, NTSB, ATSB test and confirm that NO PED on the market today will not cause interference on board an aircraft.
The leakage of RF from consumer products is on the increase, especially with "no-brand" products making an appearance in the marketplace.
For instance, I have replaced the bulbs my bedside lamps with LED bulbs. When the LEDs are switched on I cannot receive digital radio reception with my bedside digital radio.