Hows that old saying go..."even a blind hog finds a root every now and then".....ther is a difference in "impossible" and "improbable"....im glad your friend was able to get the draw on the hog, but whats the odds of it happening twice?....im not knocking anyone that does carry a gun..hell im a federal police officer...i carry a gun for a living....if you are an expierened hunter/marksman and its your dogs on the hog, then fire away....if you doubt yourself or its not your dogs, leave it at the house.
I don't know what the probability is of it occurring again.... But, he'll have his gun handy in case it does.

I personally am not confident enough with a handgun to shoot over my dogs. That's why I keep a 16" barrel levergun on my mule with me.