I'm guessing all his candidates have high IQ as the lower ones already have been filtered. He is not talking about the difference between 100 IQ and 140 IQ, but

I'm guessing all his candidates have high IQ as the lower ones already have been filtered. He is not talking about the difference between 100 IQ and 140 IQ, but e.g. 130 and 140 IQ. So I read it a bit differently: he doesn't think that intelligence doesn't matter, but at the high end of the scale, intelligence doesn't matter as much as drive. High intelligence can't make up for lack of drive: A person with 130 IQ with a lot of drive is better than 140 IQ with low drive, but no matter the amount of drive, an 80 IQ person is not usable as a programmer. Similar to: if a jobs offers you $50,000 and another $100,000, most will take the second job without hesitation. But if you have to choose between $250,000 and $300,000 the difference in wage might not matter as much as other aspects of the job, e.g. location, what to work on and the colleagues. aka The law of diminishing marginal utility.