I mean OpenAI is not a competitor to Tesla.

But it very well might be a beneficiary of Tesla's Autopilot machine learning work. Mr Musk is not shy about sharing tech within his companies (Tesla adopted friction stir welding techniques pioneered at SpaceX [1]). Also, the patents Tesla offered to license to other automakers [2] to help accelerate the shift to electrified transportation.

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

Friction stir is really old... how did they pioneer it? Perhaps they perfected it?

Not friction stiring itself, a specific technique.