I was under the impression that what was under discussion here was more along the lines of interpersonal violence, or criminal violence. Warfare, while still violence, is a different type of violence. You generally aren't afraid to leave your home at night because of a war (unless it's right in your backyard, of course). By ignoring warfare, and other types of culturally sanctioned violence, the author is dealing more with personal violence against our selves by our neighbors.