It can there is no doubt. One punch can knock you out. One punch can feel like a fly bite. You never know unless it happens. However, in most states responding to threats or simple assault with a gun will get you locked up.
In NC try shooting someone because they busted your nose. They will lock you under the jail.
Let's try keeping this discussion realistic and intelligent. That statement is neither.
So in NC I have to actually have someone cause me great bodily harm before defense is justified? What's to say someone will stop at a "busted nose?" A "busted nose" done in certain ways can be very bad or even fatal. It can mean a lifetime of disfigurement. Many operations. That's known as great bodily harm.
My understanding is "fear of great bodily harm or death." At least that's the way it works in my state.