I don't know. Maybe he just didn't want her near his ball. ;-)

She stepped off the track, sat her dog, giving the man plenty of space to pass, he slowed down, stared at the dog and Lexi let out one bark. This man began screaming at Ellie about her vicious dog that should be euthanised immediately and he was calling the police. Ellie apologized and got her dog to the car and left quickly. She said she would never go back to that track again. I walk there every week with both dogs and have never had an encounter like that. Guess I have been lucky. We have gotten so PC as a society and have NO tolerance for it, especially in breeds that are bred for it.

"Let me give you a couple of other reasons why I hold this view. In virtually all older texts describing the police service dog breeds a few points were always made. They were that the dogs show mistrust and aggression against strangers and that they are very devoted and loyal with the family and very loving with children. To me this combination of qualities stem from a very strong closed pack oriented social behavior. That means loyalty and devotion to members in the pack and aggression against all outsiders, even those belonging to the same species.This form of aggression is not very common in our dogs anymore, because many people find it to be socially unacceptable. Dogs today are supposed to be social and to a certain degree friendly. And while I see nothing wrong with a social dog, I personally also see nothing wrong with a socially aggressive dog. These dogs are not unpredictable menaces to society or vicious animals."
"It is in the dog, that is true, and it will not go away. However, as the Armin article described, you can train the dog and control it. This is not about pushing the handler around or trying to bite the handler. I have found it to be QUITE the opposite. I would never describe any of my dogs who I consider to possess this trait as "jerks". All of them were/are exceptionally intuitive and VERY connected/bonded to me. Very willing to do what I ask . Sure, they did act like puppies when they were but I think people are starting to add things to the discussion that don't have anything to do with social aggression. It is the desire to protect territory and their person . That is the simple way to put it. The protective instinct is rooted in social aggression. Normally, maturity makes a rather significant difference in these dogs, along with proper training and management....."
"I simply tell my dogs to sit. I expect them to be able to tolerate strangers within a normal talking distance. I do not expect them to tolerate petting or stupid behavior from people...it's that simple.

Forgot to mention the other difference there is that Grizz also has not just high SA, but also high defense and a low threshold for it. So he's often expressing reactive aggression as well as active, sometimes one or the other, sometimes both at the same time. And there's a bit of insecurity there at times, which brings out not just the defense but also more of the bully side.