I think it pretty unlikely that the security apparatus of the US would not able to identify Satoshi (or plural as the case may be) rather trivially. And I bet that the guy is (or guys are) pretty aware of that.
I'm pretty sure I can post an article to the internet without leaving any trace. As good as your intel may be, what possible digital paper trail could you not avoid leaving behind?
For the purposes of planning, at least, I figure that the US has fairly complete logs of pretty much ever data communication made over the Internet and the telephone systems as well as and ocean of information on travel and spending by individuals.
Satoshi did not do one article. He interacted with various developers in various ways and with the source code repository for a significant period of time and recently enough that the data collection systems were in full swing.
One probably could cheat the surveillance system with extreme skill and caution but it would be really hard to do for any complex project.