If anything, I would think the Spring Hill, TN plant would be a wiser choice. While I no doubt would love to see the employees be working at both plants... the TN location is newer, with a more recent overhaul... and soon to be idled as they move Traverse production to join the other 3 Lambdas. It is also the birthplace of Saturn.
Now... Wilmington would also make sense if the new Saturn is making Renaults or their subsidiaries vehicles... and need to be closer to a port to ship overseas as an overflow location.
1) Why would Penske want to burden himself with that sort of overhead when he can just rebadge cars?
2) Assuming he DID take on that much debt, develop R&D, develop design assets, build a huge physical and human infrastructure, why would he want to do so in union states?
I would bet that if the Penske program works using first Saturn's waning production schedule and then Renault for inventory, he will sell the network to Renault and walk away with a BUCKET full of cash. Forget all the emotion - think of the financial aspects and potential.