They will and can leave it off. You get a ticket for not having a tag, not the dealer peeps. I bought my Saleen in VA and never put a front tag on it. I even had 20% tint in a state that has tint nazis for state troopers. Never got stopped.
The dealer I got my car from did have a source for an "L" shaped piece of plastic that attached under the center opening in the front fascia. The vertical surface of the "L" was in front of the bumper, but not touching.
It was Freedom Ford in Hampton, VA. Sorry I don't know their number (I am in TX now).
Good luck and stick to your guns. I too would refuse delivery of a car with holes drilled in the fascia.