Ask HN: Isaacson says Musk and Altman “co-found” OpenAI? Accurate?

In Isaacson's bio it states:

"At a small dinner in Palo Alto, [Musk and Altman] decided to co-found a nonprofit artificial-intelligence-research lab, which they named OpenAI." [0]

Is this a journalistically accurate statement? I understand they were important and probably the most active investors and co-chair board members but were they listed as co-founders in any actually paperwork?

[0]https://time.com/6310076/elon-musk-ai-walter-isaacson-biography/