I'd like to retract my earlier confirmation. I did not realize we were talking about real horses. My bad!
heeeelllll no. #1. who in their right mind would try to get on top of one of those horrifying beasts? (I suppose I have a bias here, they're scary) #2. I've seen far too much evidence that riding them causes irreparable damage to the horse's spine. Why would I want to contribute to that? I'll give them a few apples and let them mosey on.
Yes. Yes, I have.