Maybe? I don't know.
But, either way, having two completely separate graphics code paths means a much larger maintenance burden than one. Even with hardware to test on, I'd consider it perfectly reasonable to decide to only support one, especially if the odd company out is one with a history of not playing ball with the community.
So what your are saying is that NVIDIA could have just sent them a crate full of low end $50 dollar hardware and been done with it? I find that rather unlikely, or rather as an end user I prefer to think that there wouldn't be that much drama over what amounts to nothing.