Since modern aircraft instruments are all digital (except for backup vacuum instruments), they can be replicated 100% on a powerful PC using an open-ended piece of flight sim software like Microsoft's Flight Simulator X, which is a likely candidate for what he used in his rig.
I programmed a few instruments by adhering to the XML-format that MS used in that particular rendition of the sim: Depending on the value of a number (for instance measured airspeed), a graphic is programmed to be displayed for the pilot to read. This is no different than how it's done in a real-world aircraft instrument, so flight sim instruments can be made to look and behave identically to instruments in the real world aircraft.
It's a pretty big hobby and some people have huge rigs in their homes. This includes many pilots, and there are many real world pilots in flight sim forums. So, I consider it completely normal that the pilot in question had such a setup at home, simply for fun and training, it shouldn't in itself indicate anything out of the ordinary. Of course I agree that it gave him ample opportunity to familiarize himself with airstrips along the way and train procedures, but he didn't actually need such a huge rig to do that. The costly physical modeling of the aircraft cockpit just suggests to me that he was very much into his flight simulator.