I didn't say "if the driver code got out". Nobody in their right mind wants NVIDIA to open source their driver, they simply want an open source NVIDIA driver. Which means we want the programming specifications for NVIDIA cards. How exactly does the programming specifications for a graphics card give you the "blueprints and detailed instructions" on how to make your own NVIDIA card? (You could also try to answer that question for the dreamland scenario of them making their own driver open source. I don't think it changes the outcome at all)
Notwithstanding the incredible amount of resources it would take to clone the card, and the fact that you'd be at least two product cycles behind once your clone reached the market... and that is, if you didn't get sued out of business for violating the NDA first.