Reining in extremists-in-training

This is a weird one. I was shopping at my local national supermarket chain today, and scored some lovely beef on sale. While checking out, the courtesy clerk (a young man who looked about 19) commented: "Wow, this beef is really red!" and I replied "The meat guy cut and wrapped it for me fresh." Then he says, "Do you usually buy dead cows?" I laughed, and said yes, and dead pigs, and chickens, and ducks. He said "Really?" and I said "Yes, but I am willing to look them in the eye and acknowledge what I am eating." He replied, "That's why I'm a vegetarian." Implying of course that he doesn't have the cojones to face the reality of being an omnivore. Initially, I just thought it was an interesting exchange, and took my groceries out to the car. But I started thinking: where does this young know-nothing get off commenting on my choice of edibles? He's just a kid, and when I thought more on it I decided that a courtesy clerk needs to learn that it's not his place to make political commentary on the customers' purchases. So I went back in and very nicely told his supervisor that while I did not mind having a dialog with this kid about it, some other customers might be offended. I'm still not sure if I did the right thing, but I wasn't in the mood for playing mother to the kid and taking him aside for a talking-to. And it wasn't my place. Just a weird day at the grocery store :)