Actually, I had a student dog with Legg Perthese. The insurance refused to pay for the surgery, even though the dog had not been previously DX, they refused to pay because they said it was a hereditary problem.That's what the bunny hop is, is the dog holding up the one leg slightly and only using the other. Kabota was doing it because he had no strength in that leg at all.
The surgery is pricey, but it works so well. Have you looked into pet insurance? That might help. Especially since your dog is not diagnosed with HD yet. In fact, you've been told he definitely does not have it. I'd look into pet insurance before you get a diagnosis.