1. The person has the time and money to become proficient with a handgun as well.
2. The person has no interest in owning a handgun, nor ever carrying.
I'd say, 9 times out of 10, a small frame revolver is the way to go. It covers all the needs, shooting a shotgun at a pistol range is not so nice and training is all on a single weapon with cheap range ammo. Not to mention that going around corners with a long gun sucks.