One thing I don't like about him is that if your cat comes up FIV+ he won't let you take your cat back, he puts it to sleep right then! I'm appalled by that.
How can he get away with that? If the owner wants their cat back, he lawfully has no right to euthanize it and can get himself into trouble if an owner pursues it.
Besides that, cats can live with FIV for years and be otherwise healthy.