NVIDIA creating an open source driver (well, throwing code over the wall once in a while is still open source I guess) does not mean there's an upstream driver. The kernel maintainers have already noted that it's definitely not in any shape to be merged upstream (and would need close to a full rewrite)
"He's resigning because he thinks the community should focus on that driver instead now" is completely false and I have no idea how you even got to that conclusion. Literally on the same day he posted this email, he also posted initial GSP support which specifically gives us a bright future in nouveau, as it means we can now do funky stuff like reclocking (and which will be further developed by some other people in his team at RH).
So there's quite a few errors here:
That clears up my specific confusion perfectly! Thanks!