That's a good point.
I remember reading about a lady who wanted to protest a certain comic book she disagreed with, so she went around her town buying every copy she could get her hands on, under the logic that there would be no copies for the kids to buy.
Of course, it backfired, because with the sudden boom in sales the management of the stores just ordered in even more copies the next month and the distributers were so pleased with the demand that they included bonus issues and give-aways.
Okay, snakes are not comic books, but the same logic applies; buy the store out of the snakes this month, and they will have even more the next.
The only way to stop a store from stocking a certain item is to prove that it isn’t profitable for them to carry it. When dealing with living creatures we care for, this makes for a hard line with no clear black and white answers. I immensely respect people who are able to ‘rescue’ snakes in distress, but at the same time, in the case of ill-suited pet stores, it can be a double edged sword.