And if they won't sell it to you, you walk away. Classic negotiating success, which is what Caldwell did here.
It just so happens that what FB were selling was a position of some repute within their organization, which they not only failed to do, but they misrepresented the product in the first place.
I thought that I covered this in my comment under the "dumb" option. I don't mean to be disparaging, but I'm not sure how else to take the suggestion, so switching to a not-great analogy:
Your suggestion is sorta like saying that people should walk into a car dealership and say "I want to buy this car. No, not that one. THIS car." It's a classic negotiating fail. If you know they're going to buy the car/company, you're going to milk them.
Of course, FB may think that THIS car/startup is absolutely perfect to acquire, but it's unrealistic to expect them to reveal that bit of info.