Also - most of the discussion in that thread is actually OSS sound driver (Open Sound System - a closed source alternative) and not the nvidia chipset.
I think it was dishonest to claim that NVidia was lying when they say they support Linux. It may not be the best support in the world, but it seems the only major issue is with the audio.
The audio chip they are using is not theirs and there may be NDA issues with them causing NVidia to not be allowed to write a good open source driver for the chip.
I don't know for sure, but my guess is that if the chip maker for audio allowed specs to be released, there would be better kernel and alsa drivers for it.
Thus for NVidia to support it better in Linux they would need to release it as a closed source driver or have developers work on it who have not seen the technological information that might be under the NDA.
If the audio is not good enough, you can buy a closed source driver. The other parts of the NVidia chipset are decently supported by the drivers NVidia provides.
Sure, it may be a PITA if you have to buy a driver to get good sound - but there's so little with Linux anyone has to ever buy - so you still come out ahead.