Keep in mind that in the early flex days, one saw thrust settings below climb thrust. QF, being one of the first, had a case where the crew complained to ops engineering that, on the call to set climb thrust .. the FE pushed the throttles up. Wal Stack, boss at the time, thought that a little strange so he imposed a limitation that flex would not be less than climb thrust. This tale he related when I was an undergraduate aero eng student and he was an Industry lecturer for one of our courses at Sydney.