Adding Mast or Proviron is basically the same thing as adding a very weak AI. Masteron was developed as a cancer drug for women with estrogen dependent breast cancer. Proviron also has a weak affinity for the estrogen receptor, helping to keep estrogenic sides under control.
I'm not aware of any direct reaction between T3 and estrogen or the aromatase enzyme. Not saying it's not there, I've just never heard about it if it is. Most likely any benefit from T3 as it relates to estrogen is from lowering body fat levels. For men, the Aromatase enzyme is almost exclusively produced in adipose(fat) tissue, meaning that by using T3 and lowering body fat, one would reduce production of aromatase enzyme and decrease aromatization.
Lowering body fat levels is the single biggest factor for controlling aromatization in men, other than use of an AI.