Cup2 is still street tire, not race slick. Porsche 911 GT3RS, GT2RS and most of the super cars are carrying cup2 as stock tire. Roadster prototype is also using cup2. Don’t see any problem adding it as an option to Model S.
This is not exactly true.
The Cup2R tire is very different to the standard Cup2.
Honestly, putting the Model S on the Nurburgring is ridiculous. Everyone knows that it's a poor track car far worse than the Model 3.
At least obviously Porsche had success in getting Musk and his fanboys attention.