Honestly, it is not Walmart's fault... it is the manufacturer of the knock-off fabric that is to be faulted. Walmart cannot check each piece of fabric to ensure that it is copyright infringement free. That is the job of the manufacturer that sells it to Walmart.
I cannot imagine, unless it is some scary place in China, that someone did not get permission to mass produce a fabric that looks so similar to Tula Pink's fabric. I do agree that someone didn't tell her because she SOLD her design to Moda and it became property of Moda.
Her tirade does make quilters who use Walmart fabric look pretty pathetic though. Birdcage lining, indeed. I rarely use Walmart fabric (unless I am making a bag or pillowcase), but when I first started quilting I did... because I didn't know better and because I couldn't afford better.