Goddess Nemesi wanted to degrade and humiliate this guy and she did it with her shit. She was not going to let the guy get away without being punished and humiliated. That is why she cruelly used her shit to teach him that it would be good for him if he learned to obey her. He did not want to do what they agreed and he had himself to blame for what happened.
Goddess Nemesi had an issue with this guy and she had to punish him. This was because she did not like what he had done and she had to dominate him so that he learned his lesson and he did what she wanted him to do. He was shocked and he cried and begged her for mercy but she did not show him any. It was fun for her and none for him.
Goddess Nemesi did not like how her junior did not like taking instructions. She had instructed him what she wanted done but he did not do it. That pissed her off and she had to degrade him. That is why she had to shit on him and make him drink her pee while at it. He had no alternative but to do as the mistress had ordered him to do.