Did FB really think it was going to remain a secret? "Unsending" messages that have already been read by the recipient is difficult to hide, and especially when you're the CEO of FB one of those past recipients is going to pick up on it pretty quickly.
Either FB knew and does not care, or their PR folks are completely incompetent (or in the dark), or hubris at the highest levels.
Third option: Zuckerberg said, “just fucking do it,” and they just fucking did it. Total control is very much a double edged sword, especially when the person in control seems to have only a tenuous grasp of human nature.
Either FB knew and does not care, or their PR folks are completely incompetent (or in the dark), or hubris at the highest levels.