Mistress Nica wanted to use her shit to correct this wayward slave. She felt that he had become too wayward for her and that she had to torture him for it. He did not do what she wanted him to do and that pissed her off so she had no choice but to shit on him and make him learn that there were consequences for the behavior he had and that it would not be tolerated.
Mistress Nica wanted her assistant to learn to do things the way she wanted. She had tried to talk to him but he did not want to listen. She felt that he was a good assistant but he needed to make a little adjustments and that is why she had to shit on him and change him instead of her trying to recruit someone else. The punishment worked and he changed.
Mistress Nica was there to give her friend moral support as she punished her slave. She wanted to supervise as her friend did it to ensure that her friend did not chicken out and that she did it the way it was supposed to be done. She also helped her friend to make sure that the guy regretted everything he had done. This was by both of them shitting on him.
Mistress Nica had elaborate plans that this guy messed. She was not one to talk too much but she acted. She had to act so that he knew that whatever he had done was not acceptable. That is why the mistress made him a poo slave and recorded as he was forced to eat her shit and drink her pee. He never tried to mess anyone else's plans after that.