Personally, I have never seen a situation where positive reinforcement methods have put a human at risk. As with any other training method…if done incorrectly, one could fail to correct the problem they are trying to change...but there is no point in arguing the details of our methodologies.
I think one reason that we see more cases of people dealing with problem dogs, is that when I was kid, and probaby you too. If your dog bit a kid you did either one of three things: you told the kid "don't bother the dog anymore", or you took the vet or the shelter where it was euthanized, or you took it behind the barn and shot it. People didn't want to understand why their dog bit, and they didn't really care, and they didn't think they could change the dog. Now people view the dog as a family member that you don't give up on, and many set up unrealistic expectations for the dog. People with problem dogs have to become instant experts, and they have people tell them they don't have a good relationship with their dog, and that they screwed up with the dog as a puppy because they were too lenient,or too harsh. When all they really want is a technique to improve their dog's behavior.
I am rambling....