A good writer can probably change his/her demeanor and style in writing when changing personas. I'm sure it's hard work, but I'm also sure that practice makes it possible -- at least for some gifted people. It's also possible that Satoshi isn't a single human being, but an organization that can dedicate a lot of effort to this sort of thing.
Anything is possible, but not everything is equally possible. I consider it most likely that bitcoin was developed by the 3-4 people who still worked on digital cash schemes after Chaum's scheme failed in 1998. Of those, Nick Szabo (with British spellcheck) is the strongest candidate for being the one who held the Satoshi keys.
