I've never heard of chicken-assisted therapy, but I think it sounds great!
I have one house chicken, and it wasn't intentional. She was given to me by an employee at a farm store when she was the only layer in a brooder full of broilers, larger chicks that were picking on her.
I couldn't put a single chick in with any of my adult birds, and it was September -- too late for her to fully feather out before the temperatures dropped anyway. So, Dottie was only supposed to be in the house until spring. Unfortunately, her early experiences with other chickens left her terrified of them. All of my attempts to get her integrated with other birds, even one other chicken, failed.
Dottie lives in a large wire dog kennel and has a plastic tote nest box. As she was a "mystery chick" at the feed store, I had to wait for her to grow up to know that she is a Prairie Bluebell Egger.
Until the addition of the newest overly friendly rescue dog, Dottie spent a lot of time out of her kennel; she gets along fine -- and will lay down -- with the other dog and a blind housecat. I know chickens are flock animals, but she doesn't seem to mind that her "flock" is made up of absolutely no chickens.
Dottie is very smart; she knows she likes non-GMO multi-grain chips (which I do not intentionally feed her) and learned to recognize the bag, climb into it and help herself.
Dottie likes outdoor field trips, which she takes on the other side of the fenced-in part of the yard where the rest of the chickens hang out. She knows the command "perch" and will ride on my arm.
Keeping Dottie indoors for 4 years has meant a lot of feathers, dust and dander in the house. If I could successfully move her outdoors, I probably would. Also, I think it's impossible to house train a chicken.
Aside from Dottie, only brooder chicks get to live in the house and only until they are feathered enough to move to one of the coops. Seven little girls will be moving out in about four weeks.