(5) Any other portable electronic device that the operator of the aircraft
has determined will not cause interference with the navigation or
communication system of the aircraft on which it is to be used.
(c) In the case of an aircraft operated by a holder of an air carrier
operating certificate or an operating certificate, the determination
required by paragraph (b)(5) of this section shall be made by that
operator of the aircraft on which the particular device is to be used. In
the case of other
aircraft, the determination may be made by the pilot in command or other
operator of the aircraft.

So in the case of an airline (air carrier) the airline makes the
determination to allow, NOT the pilot.
In a private plane, the pilot can decide to allow.