Many experts have shown that hardware specs which are sufficient for writing drivers are entirely useless for making hardware, to someone already versed in the field.
But they don't need to provide that source, just hardware specs. Gallium3d already has shader compilers and schedulers.
Closed source drivers make it more difficult for patent owners to check, and launching a lawsuit without evidence of infringement is very expensive.
If one has enough info about nvidia hardware in order to make a driver for nvidia hardware, the same info is not enough to make your own nvidia hardware clones.
"Very low serial numbers, like very low MAC ID addresses, are a hallmark of the “ghost shift”, i.e. the shift that happens very late at night when a rouge worker enters the factory and runs the production machine off the books"