If there's one thing that Mistress Iside has really done well, it's been to learn exactly how to really smother another person. She has this guy on his knees and she chains him up so he knows that he's not getting away from her. That's when she get on her latex gloves and smothers him with them. One hand is all that it takes to completely cut off his air supply.
This mistress does not like dissent and she felt that the way this guy disagreed with her was tantamount to dissent. So the mistress choked him by hand smothering him. That way, he would know what he did wrong and he would never do it again. He cried like a kid when she hand smothered him and that is how she knew that her punishment was effective and would achieve its goal.
This mistress did not like how this guy acted like a joker. He was an employee of this mistress and she did not want jokers working for her. He had to learn to do things her way and that is why the mistress decided to choke him. He was shocked and nearly shit himself because of what she did to him. But it was a wakeup call for him and he changed.