I do wish that people would not speak with authority about things that they don't know nothing about.
In both the F4 Phantom and the Tornado F3, the 2 stick variants were fully mission capable. In the F4K and M the RAF normally removed the stick when a navigator flew in the back because the radar display could not be pulled out to its design position. It was, however, perfectly possible to use the radar with the display fully stowed. Most Pilot Instructors managed to use the radar as well as fly the aircraft! Many other nations, particularly those equipped with the F4E kept rear sticks fitted throughout and trained their WSOs the basics of how to fly. Conversely the USN and USMC had no 2 stickers!
In the Tornado F3 the rear seat control columns remained fitted in the dual control aircraft throughout.
As for command eject, the concept of command eject in a two crew fighter was different to that of an instructional aircraft such as the Hawk. BAE and the RAF obviously thought that they would not want a student in the front to be able to eject an instructor in the rear seat. Clearly, little thought was given to the use of command eject when flying a "passenger". We will see if the Accident Investigation makes any comment or recommendation in this area?