Mistress Nomi was out to dominate and to degrade and that is why she chose to use her pony play fetish on this guy. The guy never saw it coming and he was shocked at what happened. The mistress knew that the best thing to do to the guy was to use her pony play to dominate him and that is exactly what she did to him with the help of her friend.
When mistress Nikki, mistress Rafaela and mistress Mini caught this guy lying to them, they had to pass a message to him that they did not tolerate lying and that he had to change. So the mistresses forced the guy to be their human pony and he had to carry them all over. He cried and wished they would stop it but they did not. He had to endure it all.