Well said, I totally get what you are saying. You have an amazing point that not only a human woman having sex with a horse is not only wrong and immoral because it's bestiality, but it's also wrong because it's super sexist as well.
Kind of like how the plot of King Kong of a white woman who is in love with a giant kaiju gorilla is not only bad because it is bestiality, but it's also super sexists and racist as well.