Those signing this petition pledge not to shop at Walmart on Black Friday. Many pledge not to shop at Walmart at all until working conditions/wage issues are resolved. (See the comments of each person who signs.)
Unless workers can organize, the potential for mistreatment as business conditions change is huge. A positive, well-negotiated relationship between an organized workforce and a business results in a better environment. Also, no one should have to work for less than a living wage. Some workers may chose to work part-time and that's fine, but it should be the worker's choice.