For a supposed computer guy he has a very crap website, obviously not updated since 1994 >_< he has ads on there for all sorts of unrelated crap, it is quite obviously not a genuine site for a computer retail store.
Nissan should have offered him money for the names in the first place. However...
I am not at all convinced of this guys "innocence" myself, without having heard all of the evidence of course, but his story reads just a little too much like he has tried to be clever (the fact it was his own last name probably made him think he would get away with it) and failed, Nissan cars have been known as Nissan not Datsun since the early 1980's how could someone who proportedly was in the motor sales business NOT know that in 1991 when he first registered the name. *suspicious* - I am amazed it took Nissan until 1999 to try to get the name though.
I know someone who tried this with a major company, it failed miserably, but they weren't stupid enough to try to fight it.. they surrendered after a certain amount of legal strong arming.