Life is inherently violent, always has been and probably always will be. The planet we live on is violent with earthquakes, hurricanes, volcanos, etc. Animals in the wild are violent when they kill their prey. To expect it to be otherwise is unrealistic. What most of us don't expect is violence against ourselves. This is also unrealistic, judging from the news we see in the media every day. We should expect it and be prepared for it; after all, isn't self defense why we carry?!?
I think the information in this textbook does a great disservice to those who read it, right along with all the other propaganda that we shouldn't defend ouselves, just call the police and everyone will be fine. which we all know will probably get us killed.