Huggy,
Just a thought, but assuming that an incident involving evacuation is unlikely to occur in cruise, I trust that you'd declare the incident as a critical phase of flight and have the cabin crew go around pulling peoples' headsets off in preparation for the landing?
As an avionics specialist I think that the issue is well overdone. The aircraft systems are far more likely to cause interference than a PED. In fact I believe that a lot of the unreproducable avionics defects that we suffer are caused by cross-interference between systems. Many avionics systems leak as much or more than the levels measured during the PED testing documented in RTCA/DO-233
**********************************. .Through difficulties to the cinema