Okay, we're back on track. The floor is definitely going to be demolished and re-poured next week. The builder and his concrete subcontractor are standing by their product and are going to make this right. I'll keep you all posted. Thanks for all the advice.
No real structural problem with setting light equipment the next day - especially in your climate with the warm raw materials in the concrete. They usually walk on the slab and saw control joints for crack control in 6 or 7 hours.
The only problem could be scratches and scuffs on the concrete. Make sure they use some cardboard or similar to eliminate cosmetic problems.