The tires cannot even be exposed to below 20F according to goodyear, it would be a big hassle to have separate tires/wheels just for shipping how would it even work?
One way could be reg wheels/tires bolted on car, zl1/1le wheels shipped in heated transport, dealer swaps them out and ships them back to the factory for reuse? that would be the best way imo since your zl1 wheels havent been touched more than necessary and youre not stuck with technically used tires/wheels to sell, but also very costly, 2x shipping bills.
Probably the most economical way would be ship the car with the rear ss pirellis all around on the 1le/zl1 rims, the dealer gets the goodyears separate, and swap them out. The problems with that are the dealer now has 4 tires that could probably be sold as new, but they technically wouldn't be new, and your brand new car has now had tires unmounted/remounted an additional time, even if they didn't balance the original tires(so you dont have weights added/removed) at the factory you would still have the chance of marks on the rim lip.
That is why they do this, you have just under 3 months of no orders for these cars, with enough notice that you can place a few extra orders (if your allocations allow) to hold you over until march.