Musk is entitled to produce proof
But the SEC claims he only talked to the Saudis once, and got no commitment and didn't even discuss price. Shortly after he made his "funding confirmed" tweet naming the $420 price. Unless he can produce proof showing otherwise, this is an open and shut case.
As for Musk being CTO, the meaning of "officer" in a corporate sense and a title saying you are an "officer" are two different things. They can give him a position where he's basically the 'inventor' or 'problem solver', but he won't be able to make decisions for or speak on behalf of the company.