Being unwilling to use a lethal weapon like a gun and telling others of it could be seen by someone potentially ignorant as a sign of weakness. Possibly giving someone a motivation to infringe upon your personal space/peace, because you're declaring if they take the threatening of your life/liberty to the extremes you'd be unwilling to use a lethal weapon in kind which could be seen as a lack of killing intention. Which could be seen as a weakness.

Not using a gun could or may be a sign of strength but the danger of someone ignorant to see it of the opposite perspective is in itself an unnecessary risk and inherently a survival based mistake, so the proper action would be for someone who detests firearms is too own a firearm and be willing to threaten others with the risk of death by aiming at any human who would be willing to infringe on their personal space/freedom but to actually never actually fire the gun. A bluff if you will. Similar to a pacifist bodybuilder who exercises with the intention of gaining an intimidating muscle mass to ward off threats.

This is all assuming of course the main person in question actually desires to live.