Your quote suggests Cantrell thinks he's smart, not that he's technically competent, let alone competent enough to actually understand the nuances of the technology.

Getting the powers-that-be to understand technical intricacies is as much about having someone able to explain concepts well to someone who is not a domain expert as it is about having someone who is not a domain expert able to reason about problems with an incomplete understanding. That you can explain technology to Musk and get him to ask relevant questions or that he can pick up enough jargon and specific concepts to hold his own in a casual technical conversation doesn't mean he's an omni-genius let alone that he understands the technology.

Yes, "ideas guy" is an extremely uncharitable way to put it, but that's why I said "at worst" that's what he is. The Tesla cybertruck and the Hyperloop are certainly ideas guy products (the latter literally because what he envisioned is so nonsensical none of the so-called implementations actually have anything to do with it and those that try obviously underperform even moderate expectations). Clearly many things he's heading have worked out better than that. But if you look at the actual things he's done himself and his actual biography (rather than the hagiography he has created for himself) he is a lot more underwhelming and his success much more a product of being in the right place at the right time and hanging onto the right coat tails (e.g. Peter Thiel, who is equally despicable as a human being but clearly more technologically competent).