Not true where it counts. Sure, the distance traveled at the bottom will be much greater than at the top, but the change in angle will remain constant at any point along the shaft. Proasailor got it right.
The reasoning is, I suppose, that one can build a .32m2 without changing the design rule, therefore, the RD can impose it as a safety requirement. Just so happens that ERNZ and LR already did.
Bottom line I think is, the original rudder rules stay, in addition, the "recommendations" requirement of 0.32 m2 minimum area must be met. AR's class rule legal rudders are too small area wise, and their modified rudders are too wide for the Bmax rule. One could always go forward with the cord...