Mistress Nyx did not want to deal with illogical people. That is why she stopped dealing with him and debating with him. She had to teach him to stop being illogical and do what he could to be as logical as he could. That is why she cruelly ballbusted him with her high heels to drive her point home. He learned his lesson and he did what the mistress wanted.
Mistress Nyx wanted her slave to be a macho man and she had to teach him how to be one as he had no clue how to do it. She started by hardening him. She went the route of ballbusting him as she knew it was very painful. The mistress then ensured that the slave learned to tolerate that pain before she changed the lesson and taught him something else.
Mistress Nyx told this guy that she would only let him off the hook if he managed to cum. But as he tried to jerk off and cum, she ballbusted him. She would kick him in the nuts or crush and squeeze his nuts with her hands. That is how he was punished and made to regret what he had done. And by the time he managed to cum, he had felt a lot of pain.