It's the opposite - it's a PR stunt to try to keep Sam Altman from discounting OpenAI even further and selling it to himself at a laughably low price.

Hardly Musk's first attempt at blatant market manipulation. Hell, that was how he got stuck holding the bag with Twitter

And in trouble with the SEC by claiming someone he was going to take Tesla private.

It seems unlikely that he'll get in any trouble with the SEC this time around.

What market is openai trading on?

Just because a company is not being traded on the open market doesn't mean it doesn't exist within the context of a market economy