WalMart is a very savvy retailer, and shelf space is an important asset. They would not be stocking an item unless they have determined that there is a demand for it. If they have stocked it based on speculation of demand, and then realize over time that it is not selling, they will remove it and replace it with something that will sell.
The comment: "One could argue that since they have some on the shelf not that big Of demand" is illogical. Retailers display their goods so that consumers can see and buy them. It's illogical to argue that because they are displaying the product that there must not be much demand.