We don't regulate companies to prevent "the worst of the greed" except by some naive definition. We regulate them so they mop up or don't leave messes in their wake, be these messes social or environmental.
Companies don't poison the water or use bad labor practices because they want to. Large organizations (Boeing, the Catholic church, the FBI, etc) don't "want". They respond to incentives. Companies do it because it's less un-profitable than the next best option and to not do that while their competitors do puts them at a disadvantage. Regulation only adjusts the incentive scale.
>You have to ignore all of these constraints to arrive at the simplistic "greed is good" conclusion
You have to ignore the difference between "good" and "can be harnessed for good" to come to that conclusion. You're implying meaning he didn't write because it makes a more easily defeated position.