This actually is a legitimate interstate commerce issue though. Local governments should not be able to target certain retailers to coerce them into supporting illegal activity.
By today's hopelessly liberal reading of "interstate commerce", pretty much anything is justified. But in this case, if you want to pretend that you respect the intent of the Constitution, no way this is a fed matter. Even though we all can assume most day laborers are illegal, you can't automatically equate one with the other. I could be a day laborer if I wanted. Someone with legal status could be a day laborer. So no, forcing Home Depot to accommodate day laborers is not the same as forcing them to accommodate illegals, even if the net result is the same. In fact, the locals could rightly BLAME the feds for the fact that so many day laborers are illegal. The locals just want to corral them into one place, and being local gubmint, they were able to force the business to do it. The feds job is to enforce immigration law, not local zoning law.