You are contradicting yourself. If destroying the company isn't enough pretext to get you fired but an affair with a subordinate is, then it's a big fucking deal that would have been an issue regardless.

They needed a pretext because if the board publically confirmed how much damage he'd done to the company, it would hurt the company even more through investor and employee panic.

When has legal fallout from an affair with a subordinate ever destroyed a Fortune 100 company? That doesn't happen.

You are not making any sense. Was he destroying the company or not? What kind of destruction does not have obviously visible signs (to everyone) that can be acted on? What Kind of board sits down and decides that the destruction of the company is worth investor panic because 'it's worse than it looks'. What, are investors going to be calm as he destroys the company?

Are you even hearing yourself? Do you think a CEO is King or what that they are destroying a company and that's not enough to get booted? CEOs get fired all the time. A Board certainly doesn't need an affar pretext to boot one that is tanking the company.