Why does everyone say that Nate cheated? As far as I can see testosterone injections when perscribed isn't cheating. He didn't follow some regulations.
Obviously he didn't follow the way they were prescribed if his levels were so high it would be considered an unfair advantage (this is the "cheating" part) leading him to be unlicensed.
This, and I'll add: it is not illegal to use TRT if you have low levels of testosterone in order to boost it back into the normal range - it's going over it that is illegal, which was exactly Nate's case.