This guy made mistress Iside feel like shit and she did not want that. She had to teach the guy a lesson and she did so using her human toilet fetish. That is why the mistress had to be as cruel and humiliating to him. That was not to be repeated and the guy learned the hard way that the mistress would not tolerate such nonsense from anyone ever again.
Mistress Iside was so angry at this guy that she had to shit on him. The mistress was so disappointed and angered by the things he had done that she knew it was important for her to scare the shit out of him so that he would not think that everything was ok when it was not. That is how he changed because he realized that he would be in deep shit.
Mistress Iside felt that this guy was too lazy for her and she had to find a way to deal with him. The mistress felt that the best way for her to dominate the guy and ensure he would never be lazy again was for her to make him eat her shit. And that is exactly what the mistress did to him as she turned him into her human toilet.
Mistress Iside wanted to test this guy's oral skills. He wanted to nail her and he told her he was going to do to her things she had never experienced before. And since she wanted that, she agreed. But to avoid disappointment, she had him eat her ass and her shit first to test him and his resolve. She was shocked at how well he ate her shit and her ass.