His use of "brilliant" has little to do with IQ. It's a conflation of (a) creativity (which correlates, as he observes, with manic-depressive patterns and unreasonable expectations of others) and (b) superficial charisma (which correlates with narcissism and substance abuse). Those are two types of "flashiness" that he makes the mistake of conflating.
I'm category (a): creative, prone to mood swings, basically reliable but bad at the superficial reliability contests that determine advancement in most organizations. Yes, someone like me can be detail-oriented and show business acumen. We can be reliable. We're just not as competitive at being reliable (especially in the superficial ways, which are important in customer service) as others. If you need +3 sigma reliability-- someone who can work 100-hour weeks and not miss details or break rules or even become annoying-- you don't want +3 sigma creativity.
Does "+3 sigma creativity" actually mean anything?
(I'm aware enough of the rough technical definition, I mean in the sense that if you think there are 500,000 super special people in the U.S. can you do anything useful to find them?)
I was just using it ("+3 sigma") to mean "high-level" creativity and could have just as easily said "99.9th percentile" or some other number. No, I don't know of a good way to test for it.
My point is that there's a strong negative correlation, especially at the competitive upper reaches, between creativity and the sort os superficial reliability that (a) tends to determine a person's ability to advance in organizations, and (b) you'd probably want in someone you put in front of difficult clients on a regular basis.
I'm category (a): creative, prone to mood swings, basically reliable but bad at the superficial reliability contests that determine advancement in most organizations. Yes, someone like me can be detail-oriented and show business acumen. We can be reliable. We're just not as competitive at being reliable (especially in the superficial ways, which are important in customer service) as others. If you need +3 sigma reliability-- someone who can work 100-hour weeks and not miss details or break rules or even become annoying-- you don't want +3 sigma creativity.