Bush was very candid from day one of his presidency that he favored "regime change." What O'Neill is saying is nothing new. Yes, Bush ultimately "sold" the regime change too heavily based on a weapons of mass destruction angle (in my view, based on heavy pressure from his advisers), but that was only one angle.
Frankly, I think O'Neill is a disgrace and an opportunitst. If you are hired at the highest levels government, please show some class when you're fired, rather than selling a tell-all for-profit book about confidences with the commander in chief.