There are two other advantages of a small handgun in home defense. The first is concealabilty. I’m not going answer the door with a shotgun every tome the UPS guy or some girlscout selling cookies comes knocking. And I’m not going to sling a shotgun over my sholder every time I mow the lawn. But I will slip a revolver into my pocket. Secondly, a long gun can be a disadvantage in a confined space like a hallway.
He already has a handgun.