Aside from the "moron" thing, I think that jackrungh made some good points. While what this person is suggesting might only be possible in the most ideal of circumstances, I would argue that doing away with all small animals available in pet shops is as well. I have read things on this site and others that helped me make the decision to swear off pet stores, but the last time I was in one (several months ago) they had rabbits available. In addition, every spring (here anyway) every shop that could conceivably have a small animal license sells rabbits.
What seems to be overlooked (and was mentioned by jackrungh) is the general public's perception of small animals versus the perception of dogs and cats. Though it is not right, few people outside the rescue/animal rights/well-educated cavy owner world look at cavies as anything more than cute, disposable things. Heck, many books sold as "how to" books for cavy care portray them as just that.
I teach school, and I have pictures of many of my guys on my door. I spent a few minutes the first couple of days talking to my students about the nature and proper care of cavies. Even after several minutes of discussion, I had one student (high school) say, You're talking about rats, right?" There are people who would not dream of dumping a dog or cat that would have no same compunction about a cavy, rat, hamster, etc. At the moment, they simply do not enjoy the same beloved pet status that felines and canines do.
The day may never come that pet shops run as rescues, but sadly, I do not believe the day will come either when pet shops do not sell small animals at all. If you are talking about sustainable models, look at selling larger animals like dogs and cats versus small ones like GP: 1.the initial cost of a dog or cat from a breeder is much higher, 2. the upkeep (even with crappy food and poor conditions) is much higher on larger animals, 3. what to do with a cat or dog once it is no longer a cute baby? If a guinea pig doesn't sell, it can cheaply be gotten rid of as snake food.
Please don't misunderstand me, I applaud the efforts that were made to get dogs/cats out of pet shops (and the efforts that are being made for small animals), but I think we'd be kidding ourselves if we just assumed it was simply a matter of protests. If we go back to the argument that pet stores only look at the bottom line, I'm afraid that we must conclude that change came about, partly, due to dollars and cents;it simply got too expensive to offer dogs and cats for sale.