I don't really grok OpenAI's long term mission plan. "Keeping AI open" seems rather banal to survive long amid a cultural ethos as purposeful and dynamic as SV's. Perhaps the prospect of meandering their rather random path proved less pregnant with possibilities than AK had hoped.
Or maybe Tesla promises to build more than just KITT? Musk has huge ambition. I suspect Karpathy was enraptured at the prospect of sinking his teeth deep into a wide variety of tasty pies there.
As far as I can remember, most important research from OpenAI is InfoGAN. Others feel somewhat below outstanding. Their open source record on the other hand is pretty solid, gym/universe and various implementations and testing of existing models does live up to the openness in their name.
Now, granted, SpaceX does not file patents because their competition is primarily nation-states [3], but I feel thats a valid concern with regards to that domain.
"We have essentially no patents in SpaceX. Our primary long-term competition is in China," said Musk in the interview. "If we published patents, it would be farcical, because the Chinese would just use them as a recipe book."
[1] https://electrek.co/2015/05/24/spacex-transferred-novel-weld...
[2] https://www.tesla.com/blog/all-our-patent-are-belong-you
[3] http://www.businessinsider.com/elon-musk-patents-2012-11