With Alpha-Floor engaging sometime between Alpha Prot and Alpha Max, I dare say if they didn't keep those figures the same for 5 seconds there would be a few people conducting max rate takeoffs.
Considering it is only V2 that has to be 1.13 VS.
Vr's only requirements are that Vr is > 1.05 Vmca and it also allows V2 to be reached by 35 feet.