I don't believe that Walmart is the culprit. It's the manufacturer, in my opinion that is to blame.
Like someone already said...How is Walmart to know it's a "stolen" design? It should be up to the company selling the fabric, meaning the BIG company (Moda, Cranston, Northcott, etc) to be the ones to get the flack of selling the knockoffs and not Walmart or any other store.