Interesting... and so typically AF: the Z fare (which allows SU operated flights) cannot be combined with the O fare (which does not allow SU operated flights) because the Z rules date from the time there was no O fare... and they have not been updated accordingly once these O fares have been published.
Also the difference between O and Z is only 50 EUR per direction, I guess they wanted to give an incentive for fliers to take AF operated flights but they should have used a different fare code on the Z basis, like ZLS1FR at 685 EUR and keep ZLSFR at 735 EUR.
However, one of the main benefit of having award booking classes used as revenue booking classes is that availability for awards is usually pretty good, like awards in long haul premium economy which books in A class. The reason why they now cost 2x the Y level when business is just 2.5x is certainly more justified by the fact that they are widely available than by the quality of AF premium eco.