In the interest of keeping Facebook private, I'm sure they would have given out the shares with some sort of stipulation against selling them without Facebook approval. Once too many people have shares, the company would be required to IPO.
You may be referring to something different, but Facebook was exempted from the SEC rule that requires companies with more than 500 shareholders to report their financials publicly (so a public company, but not publicly traded).
That ruling only applies to the RSUs they give out to employees. If you check out the last page, it's quite explicit that normal Facebook shares and options aren't exempt.
most likely they have a contract that lists exactly who they can sell those shares to and when, with the 'who' being facebook in a large number of cases.
Let's hope for them that blabbing about the deal isn't one of those, but since this is essentially 'damages' they may have had some leverage in the negotiations.
