Boeing 777 used low altitude 'terrain masking' manoeuvre practised by fighter jets...

[JHB]

39. Anything from "fly" for fun to practicing for requalification...

...to combat sims, to just "trying out" planes he doesn't usually have the opportunity to fly. Even flights of fancy, like a plane that has all the flight characteristics of a Sopwith Camel, but the in-sim model looks like Snoopy on his doghouse, in full "world famous WWI ace" regalia.

There are hundreds of thousands of flight sim hobbyists, a significant portion of whom are also pilots. Most have a bit simpler setups, like a PC with a fancy joystick, but there's probably thousands of people who go whole hog and get all the toys. An actual pilot would probably be even more inclined to do that, just out of familiarity.

My point is, simply having a setup like his is not remarkable on its own: it's pure men, boys, price of toys-type stuff. If it has anything significant, it will be in how he used it in the weeks prior, and whatever the authorities can recover from it.