Remember how Diaspora was supposed to be the private peer-to-peer encrypted Facebook but peers private keys could be read or overwritten by anyone on the Internet? Doesn't your argument suggest "Well we can't rule out the NSA having a man on the inside trying to undermine their encryption"? Heck, why not go all the way: the NSA funded Diaspora to bring Facebook to the negotiating table?
Down this path lies madness. Software has bugs.