What am I missing here?

From Fox News Tongue Tied (emphasis mine) about a U-haul sign saying "don't hire the illegal laborers":

Tom Wilson, co-executive director of the Canal Alliance, an agency that provides assistance to local laborers, says he has received about a dozen complaints about the U-Haul company's sign.

"The tack they're taking is a particularly troubling one," Wilson said. "They're painting illegal day workers as criminals, making generalizations about a group of people."
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So let me get this straight. Tom Wilson says illegal day workers are not criminals. What part of illegal does he not understand?

Now if it's all done legally, then that's another story, but that's not what he said.