One possibility is indeed that Satoshi is trolling us hard. He may actually have based his pseudonym on this guy... but that's playing a dangerous game, as this is in fact one more datapoint to honing in on the real Satoshi.
A number of blackhats did this around Lulzsec time. They would adopt a second-level identity -- and drop very, very small hints to make people think they're some person X. Person X being a person the blackhat in question just chose randomly by, oh I dono, cruising around the web where people talk about IT security... choosing an interesting person, learning about them by googling around, and eventually starting to play that person (or rather, play that person playing to be anonymous). This was one of the suggested strategies in the helpdocs wiki, advertised on the irc channel where lulzsec members usually would be. But since Dorian is kind of an old guy, the real Satoshi would have had to know him in real life (hence my saying that it'd be a dangerous game for Satoshi to be playing).
But really, I think it's just a very funny coincidence. As others have pointed out, Satoshi Nakamoto is not that of an uncommon Japanese name. Too bad Dorian got dragged into all of this. He seems like a sweet old man, with a great sense of humour ("I want a free lunch", wonderful) and an awesome hobby (model trains are fun). I'll buy you a lunch Dorian!