Broad general statements are fine, but....
Leaving aside the idiot behind the counter for a moment, a lot of you guys are missing an important point.
And that is the individual getting the gun. We know guns, and tons of things that are so basic that we assume "everybody" knows them.
We are interested in guns, shooting, self defense, CCW, failure drills, etc., etc., etc. Lots of folks aren't. And even some of those who are slightly interested don't have the skills developed (or the personal situation to develop the skills) to be confident, and able to use them effectively in a high stress situation.
Look how many times it get mentioned on the boards about "what if, if the heat of the moment, you forget to take the safety off?" And there we are talking about "experienced" shooters!
I'm not sure how you can't have enough strength to rack a slide, but still have enough strength to pull the double action trigger of a revolver while steadying your hand and handling the revolver's recoil.
This all depends on the individual, and the gun involved. For one example, my mother, a small woman, (5', 100lbs, size 3.5 ring) could not work the slide and load a particular .25acp. The small auto was too tough for her, due to the size of the gripping area, and the strength of her hands. She could, however, shoot a Model 28 S&W, or a Colt Govt model, although she wasn't really comfortable with either one due to their size.
The gun SHE chose as best for her was, (get ready) a Ruger Super Bearcat! And she was very good with it.
Considering how many different things are needed to make even a simple auto run as flawlessly as a good DA revolver, for someone with no experience (and unlikely to develop much) a DA revolver is far from the worst choice.
The analogy to buying a car isn't even close, as it is a truly rare individual that buys a car without knowing how to drive, or without expecting to use the car on at least a fairly regular basis. Not so with handguns.
While it was probably the best outcome, the clerk showed several levels of ignorance getting the customer there. He wouldn't work for me very long, but then, I'm not in the business of selling guns for a living.