What I don't understand is why such a person resorts to a nickname, but does use a picture. The US government knows the real name of people like ioerror and moxie marlinspike. It seems pointless to consistently hide the real name to the public.
If your pseudonym carries more klout, and you have even more people in your social life knowing you by the pseudonym, it kind of becomes your 'real' name. Not any different from other persona names like Marilyn Manson, or Marilyn Monroe.
I used to use my online name enough that people were confused when they heard my legal name. Eventually, I decided to change my legal name to save the hassle of having a legal name that nobody actually knew me by, but that's easy in my country (doesn't involve courts or lawyers) and a pain in the ass in most other places.