Art, seems you like to over react.  The dog was off the property, and if he waited.... it would have been too late.  As I was growing up in the territory, and walked to school, the neighbors dog, a Golden, had the same behavior.  That dog went beyond the boundary many times and bit a few kids.  I don't think a dog knows precisely where the boundary is when he is in protect mode and making a charge.  Think about it....