I experienced this first hand several years ago when walking Moose and Gator. I was approached by an obviously drunk guy in a more secluded part of the neighborhood. Both dogs acted in a way that I had never seen before. I have no doubt that this was due to them picking up on MY unease.I agree with Jklasky in dogs reading people. I always tell people in my lessons that the first thing they should understand is that your dog reads you better than you read your dog.(in most cases). Therefore, dogs read you to know when you are anxious or fearful or even excited by an approaching person or situation. Just like with a herding dog, the rabbit runs through the pasture, the sheep don't perceive it as a threat and neither does a dog. A coyote is on the fringe, the sheep get restless, and the dog goes on alert. He reads the sheep as he/she will their owner and protect if necessary.
I have often wondered how accurate of a predictor of real protective instinct, aggression, and defense SchH is. Maybe someone can explain?
If you have a very confident GSD, it seems that it would be difficult to get that dog to perceive a real threat from the helper. Just one of the factors being because the handler's body language does not convey threat. Is there any way to know if this dog will fight or flight in a REAL situation, and if "no" what does this mean to SchH as a breed test. Is protection work an adequate predictor or true protective behavior?
Tying this back to the OP would it even matter what the SchH dog SHOULD do if there is no way to predict what he/she WILL do?