Article 21 has nothing to do with the requirements for radio operation. It is a requirement for Flight Crew and your wife would not be a crew member.
The operation of radios is covered by the 1949 Wireless Telegraphy Act, not the ANO.
Just look at the aircraft radio licence, it has a Schedule and para 6 states that the licensee shall not permit any person to operate the station unless that person
a. either holds a flight raditelephony operator's licence or
b) operates under the supervision of the holder of a FRTOL.
passengers can therefore operate the radio under the supervision of the pilot provided the pilot holds a FRTOL.
[This message has been edited by Noggin (edited 10 June 2001).]