I can confirm that that is what it is doing. There is no value between 1 and 0, it is either or. I think this is how it should be for superfly as that is how the Cycles DiffuseBSDF works. There is no value between 1 and 0. The Physical root works the same way. There are no values between 1 and 0. In PBR something is either diffuse or not. Workaround would be to use Cycles mats only for this. Cycles root with a mix closure then a diffuse plugged into one of the ports on the mix. You now have values between 1 and 0.

W10, Ryzen 5 1600x, 16Gb,RTX2060Super+GTX980, PP11, 11.3.740