Thanks, ladies! I appreciate your views. I had to laugh that the first reply was from a women who shares the same name as the horse in question (Hannah.)
I sent the information to the equine manager. She thinks the horse isn't right for their stable but she forwarded it to someone "higher up the chain." They have two horses there already that I feel are too risky for therapy horses but they use them for whatever reason. I know one of them is used because he has a unique gait but he and his partner like to pin back their ears and act threatening. One of them even nips! I will be interested to see them at work this Spring. Maybe then I can understand how they make it work with them.
We had/have plenty of irritable mares where I work that are some of our most prized therapy horses. I have a few bite marks from them, and once had a draft try to get her mouth around half of my rib cage or my whole thigh. (I'm a little dainty, though, but ****!)
The key to them is giving them to a handler who has the skill to handle them appropriately, and to keep a close eye on those kids and their little fingers.
If she's sweet and has the potential after she's broke to make a good horse, you should send on her info to an equine-assisted therapy program instead of a hippotherapy one. They need the mounts as badly as we do, and she sounds like she might make a good steed there after a while.
I can go off forever on my little rant of what makes a hippotherapy horse, but it tends to get me all revved up on the matter. I hate it when somebody brings in an old, broke horse with lameness issues or something, and thinks it'll be a super addition to hippotherapy 'because he's nice and won't spook at anything!' I understand they're trying to help, though, and that's always nice.
Edit: I'm not trying to sound like a bitter therapist on the whole matter, though! Please don't take anything I say that way. You can even PM me questions if you ever feel like it. :) Just thought I'd add this on as an afterthought.