If I read the OP correctly, after the son came to the door with the shotgun the encounter was over. No shots needed to be fired.
Having said that, my husband and I do not travel with a gun, although it wouldn't be a bad idea.
One time we stopped at a rest area and were checking the connection of our toad when a guy came over and was giving us a wild story about
one of the truck drivers (he pointed to)quitting his job right then and was giving away the company cash. If we would go over the guy would give us $100. Of course, we declined, but this was in the middle of the day in a rest area where it would have been very difficult to have done anything bad and not be seen. So we never did figure out what it was about.