Normally, I'd be inclined to agree, but not in this case. Constitutionally, the federal government does have the responsibility to ensure that States and localities ensure the protection of the constitutional rights of all citizens of the nation. Localities which attempt to force Home Depot to provide shelter and supplies for day labourers are infringing upon the property rights of the stores, which in turn invokes this particular reverse federalism (federalism works both ways, after all).
You haven't ever owned yer own business or dealt with local authorities, have you? Local authorities can dictate quite a lot of things that are none of the feds business. You have to get permits, licenses, abide by ordinances, inspections, etc. The freedom and rights we enjoy are far from absolute. Even private homeowners have to comply with a lot of rules/regs. Sounds to me like you've got Home Depot tolerating the presense of day laborers cuz it attracts/helps their customers who hire them. The town probably wanted some semblance of order, and so said, look, if yer gonna have these day laborers gathering here, put up a shelter. That's what I gather from this.