I'd like to think I'd answer something like, "If that's how you push me now, I don't think I'd enjoy working with you. So, if you're interested in the opportunity to invest in my company, please show me the respect of letting me assess your offer on its merits."

I doubt that would get him to change tack (unless my company was killer), but it would probably get the other sharks to like me for standing up to the bullying.

Of course, it's easy for me to say that from behind my keyboard. Doing it in person in real time is much harder.