Princess Kirstin does not respond well to blackmail but this guy did not know it and he tried to do it to her. She was not going to go easy on her and as such, she had to make sure that she degraded him as well as humiliated him so that he would never try that nonsense on her again. That is why she went ahead to humiliate him with her dirty shoes.
When this mistress noticed that she was dealing with a loser, she knew she would have a lot of fun humiliating him for her own entertainment. That is why she sat on her throne and laughed at him as she humiliated him. He was made to lick her feet as well as suck her toes while the mistress fanned herself and laughed as he struggled to do what she asked him to do.