I agree to some extent, but I still like to think integrity is a function of how you behave at all times, not just when it is advantageous.

For example in the situation above - I perceive you as the kind of person who really believes what he writes and wants to help people get up and running. I mean, your essays date back before YC.

So in my mind, advising this group during the acquisition offer, even if there was a chance you would miss out, is showing a true adherence to some kind of ethical/moral code.

That's true integrity, in my opinion.