Giordano's definitely does not use cornmeal in any of their pizzas. As far as cornmeal in that Chicago Pizza book goes, that is what Pizzeria Uno and Due's, and the old Gino's USED to be like. Now, they use coloring, which doesn't make sense because the cornmeal should be in there for flavor, not color. That "dry" recipe for deep dish is right though. The dough shouldn't be very pliable. Basically, you plop it in a pan, and just press it out to all sides. There is no rolling involved. It should also be so rich, that oil is not needed in the pan. Unfortunately the Gino's chains are exactly that--chains. They are a shadow of the original. It's been years, but I would hope that the original Gino's downtown(Chicago) still does everything fresh. The Gino's in Oak Lawn has prebaked crusts, and sausage "patties" that are simply placed in the pizza. They used to use raw italian and smash in in there, and the pizza would take 45 minutes minimum to cook. Now you can get it in 20 minutes.
Jeff Smith did a special Chicago show years ago, and had this old Afro-Amer.sweetheart on there making the pizza. She was working at Gino's for 25+ years or something. I think she used cornmeal.
For home use, I like the cornmeal ground, instead of out of the box. I think you can also use Masa Ahrina (?), which Hispanics use for their cooking.