People who jump on Ortiz may have overread the first sentence of the artice:
Cristiane "Cyborg" Santos (10-1-1 NC) reported that doctors recommend she not cut weight from 145 pounds to 135 pounds.
So it's not only Ortiz, but also her doctors. And she is no wrestler who is used to cutting weight for ages, so such a cut would probably have a bad effect on her performance.
If it isn't for the belt anyways, they can do it at a catch weight if White and Rousey want that fight so badly.