There are a tremendous number of small groups working with horses and the disabled. This has been going on in the US for decades that I'm aware of and probably longer that I'm not. And yes, it often works. Riding horses helps strengthen core muscles for cerebral palsy victims and paraplegics. Some autistic children seem to relate to horses as well.
The real help is the right horse and there are plenty of them right at home. They are big and patient and will wait for the child to make the move. They are calm and will ignore involuntary movements. Most of these programs can use more support. They need money to pay for feed and stabling for the horses and volunteers to help.
So why are we supposed to support someone who took his family half way around the world. It seems to me that his child had already found Betsy very close to home. For me, I'll send the price of admission to a local group.