Well, let's assume the current number of seats for a given flight is : X6
Now, will AF do?
1/ When the 6 six seats are taken (X0), RM opens T3
2/ The number of classic seats is reduced to (X3 for instance), and when all are gone (X0), RM opens T6
In both cases, the number of award seats indeed has increased (from 6 to 9) and the rule is "first-come, first-served". But with option 2, one pays the award at a higher price (both in average and marginally).
Also, I re-read my previous post. It makes no sense to have X and T available at the same time because as these classes have the same restrictions, non one would buy T if X is avaialble.