Mark Zuckerberg was reduced to bawling on the floor of a restaurant men's room in April 2005, amid high-pressure fundraising, says a new book excerpt published in Fortune. The Facebook co-founder's head was down, his words were panicked.

It would be an embarrassing story if it weren't so convenient for Zuckerberg, a rampaging robber of user privacy cast, in this suspicious new tale, as a young man controlled by his deeply-felt morals.

As Fortune contributor David Kirkpatrick tells it in his forthcoming book The Facebook Effect, Zuckerberg was torn up inside at the prospect of breaking an agreement with the Washington Post Company's Donald Graham, a genteel prospective investor who Zuckerberg admired, in favor of a better deal from a bloodthirsty venture capital firm, Accel Partners. Zuckerberg, you see, just hates to break his word:

Accel's co-managing partner, Jim Breyer... hosted a dinner for Facebook's leaders at the elegant Village Pub near Palo Alto. The Pub is known for its wine list, and Breyer, a connoisseur, ordered a $400 bottle of Quilceda Creek Cabernet. Zuckerberg, still only 20, ordered a Sprite. Breyer was doing everything he could to loosen Zuckerberg up. But Zuckerberg remained uncomfortable about something. Then he started to tune out, Matt Cohler noticed.

Zuckerberg went to the bathroom and didn't return for a surprisingly long time. Cohler got up to see if everything was okay. There, on the floor of the men's room with his head down, was Zuckerberg. And he was crying. "Through his tears he was saying, 'This is wrong. I can't do this. I gave my word!' " recalls Cohler. "He was just crying his eyes out, bawling. So I said, 'Why don't you just call Don up and ask him what he thinks?' " Zuckerberg took a while to compose himself and returned to the table.

Zuckerberg eventually calls Graham, talks through his dilemma, and Graham graciously releases Zuckerberg from any obligation. Graham comes away impressed with the young CEO's moral maturity: "I just thought to myself, 'Wow, for 20 years old, that is impressive — he's not calling to tell me he's taking the other guy's money. He's calling me to talk it out.' "

Neither Zuckerberg nor Facebook is quoted confirming the account, but then again they're not quoted denying it either. And the preson who provided the tale for the book, investor and former Facebook VP Matt Cohler, still works as a "special advisor" at Facebook. So it's hard to imagine Cohler speaking out of school; it's equally hard to imagine Facebook didn't at least implicitly sign off on this story. If it had disputed the tale — as might be expected from a startup eager to bolster the professional image of its very young CEO — it surely would have insisted on its disagreement being noted within the text.

But of course the company must love this story. There's no reason to dispute it, and every reason to plant it: Zuckerberg's decisions on privacy have time and time again called his ethics, and in particular the credibility of his word, into question. He's appropriated users' friends lists and profile pictures; strong-armed users into allowing Facebook to make their likes, interests and activities public; allowed partner companies to hoard sensitive user data; implemented and then abandoned an invasive and controversial advertising system; and even allegedly used Facebook password data to hack email accounts when still in college.

Amid all that controversy, an anecdote that highlights Zuckerberg's deeply-felt moral convictions is a welcome enhancement to Zuckerberg's image.

Not that we begrudge Facebook a well-executed bit of spin. If anything, Kirkpatrick's excerpt leaves us admiring Zuckerberg's steely resolve. Not moral resolve, mind you, but resolve to make boatloads of money. Just look at all the offers the CEO, still in his early 20s, turned down, according to this new book:

  • $10 million on the spot from a Manhattan financier in 2004, when Facebook had just 100,000 users at 30 schools. Zuckerberg "didn't for a minute think seriously about accepting."
  • $75 million from Viacom in early 2005.
  • $1.5 billion in cash and incentives from Viacom in late 2005, of which Zuckerberg said, "I don't really need any money. And anyway, I don't think I'm ever going to have an idea this good again."
  • $850 million in cash from Yahoo in summer 2006. Zuckerberg might have sold at $1 billion cash and was in high spirits when Yahoo reduced its offer to $850m, since it meant he didn't have to think about accepting.
  • $15 billion from Microsoft. Zuckerberg wanted to maintain full control, and couldn't quite get that.

Brass ones. Not that we'd trust him with sensitive profile data, or honestly buy the idea of him weeping in a bathroom. But brass ones nonetheless.