Regardless of what you think about him, he’s good at something. It’s not grifting; there are plenty of people good at that who couldn’t possibly hit this level of success.
As a part-time CEO, he probably deserves part-time credit.
(I am 100% a SpaceX fan, personally. Whatever it is that has made it work.)
*buy pre-existing companies
Tesla was four guys with the brand name and nothing else when Musk came along six months after founding. Given that Musk was the first large outside investor and invested in/joined the company four years before Roadster (which he heavily participated in designing) deliveries began, I don't think it's unreasonable to call him a founder even aside from such being legal fact.