Pretty much this is whats going to happen
End leaves if not admin, all mods leave
forums turn to shit due to inactivity...if new mods are made chances are they wont know how to run things as needed
vets will leave becuase site is run by newbies, or forums going to shit, or both

just make him an admin, and tell him to keep shit in check
what you paid for this site is not worth what will happen