Why is this plausible? Here are the factors:
1. Both of these organizations have workers who would have the technical expertise that Satoshi demonstrated.
2. They both would have workers who would also know tradecraft well enough to remain anonymous (which is not easy when so many are looking for you).
3. A project like Bitcoin could have been started as an experiment to create a honeypot for money traffickers, etc., and the experiment "got out of hand" and became very popular. And what would you do if you were this worker? Basically what Satoshi did: bail out and let the public sector take over the project.
4. Only the CIA/NSA could walk away from $60 billion, chalking it up to the cost of doing business (e.g. keeping their secret capabilities secret).
5. The only other plausible explanation is that Satoshi was just some individual who died and left no trace of who he was--which has all kinds of practical problems with it (e.g. why wouldn't somebody around him figure it out).
I realize this is just a theory, but I think my theory is better than all of the other theories
![Smiley](https://bitcointalk.org/Smileys/default/smiley.gif)