Lady Naomi does not like ignorant people and when it happened to be her slave, she knew she had to make sure he stopped his ignorance as soon as possible. He had to be enlightened and she tried to help him but she wanted him to know that it was all up to him whether he would stop being ignorant or not. So she sat on him with her jeans to show him there would be consequences if he did not stop his ignorance.
Lady Naomi wanted this guy to never mess with her again and that is why she chose to dominate as well as to humiliate him. The mistress used her jeans to facesit on him and she ass crushed him in the process. He could do nothing about his punishment and his humiliation. He had to endure it and promise the mistress that he would never do what he had done again.