The 'gray man' is more of a self-defense mode. When in public, never draw attention to yourself because a predator will notice you if you wear flashy clothing, tshirts that label you as an NRA member or a Trump supporter. The rule is to become invisible. Of course, if you can in your state, always go armed, concealed, and be ready to defend yourself, but appear to all outward appearances as "harmless" or better, invisible. Thus the name, "gray man."