Well, with the distance involved you can't justify use of force based on death or serious bodily injury to yourself since it's so easy to slip out the door.
So, you're left with using force to prevent death or serious bodily injury to a third person, or the commission of a forcible felony.
Therefore, it boils down to the reasons behind why one chooses to carry a means of defense.
Is it just for you and yours, or is it also for a wider purpose?
Individual answers to that question vary.
I certainly can't argue with that. Indeed, it is an individual and very personal decision. It's one of those questions that has no right or wrong answers and what we decide is usually driven by our values more than anything else.
I know without a doubt that doing nothing when I had the capability to do something to end a situation like this would haunt me for the rest of my life. But that's my values driving that.