I highly highly doubt it. I'm almost 100% sure writing about a human in ecstacy getting fucked by a horse will get you instabanned.
and yeah, I wouldn't expect them to hold their end of the deal no matter how closely you try to stay within their defined exceptions. I'd always have a back-up plan ready from the beginning in case they change their mind. like my incest game is built from the start to double up as a non-incest story, all the code is ready for switch, just because it's much easier to write it in as I go rather than revamp everything some day.
I also have some horsing around going on which I can switch to implied hidden background stuff if/when needed. (which I can do because the horse fucking isn't in any way central and doesn't have to be seen or even mentioned. it's just that there's an skin ointment with a secret ingredient, and I can just show the doc going to a horse farm to get it, and have the women dream of wild horses after using it. everybody will get it's horse cum and the girls are dreaming of more than just horses galloping on a grass plain, even if they hide it. - ofc I'd much rather show the stable girl jerking off her horse to sell the cum, and the women deaming of fucking horses, but for the story to work I can imply all of it without saying a word or showing one single horse cock.)