I believe he's referring to an acquisition by Facebook being an exit option, not an acquisition of Facebook.

Investor sentiment (as irrational as it sounds) is very important. The "apparent" failure of FB IPO along with the less than impressive performance of web 2.0 companies in the public markets have casted a dark cloud in the industry. Nothing has changed in the material sense, but this narrative is a great opportunity for investors to bargain for better deals.