I don't see it as much of a plot hole; I'd assumed he'd previously had an interest and had some replica stuff lying around (as people do today) and so when he needed an escape he had them to hand for his fantasy/delusion.
Babylon5
It was the dawn of the third age of mankind. Ten years after the Earth Minbari war. The Babylon project was dream giving form. It's goal to prevent another war by creating a place where humans and aliens could work out their differences peacefully. It's a port of call. Home away from home for diplomats, hustlers, entrepreneurs, and wanders. Humans and aliens wrap in two million five hundred thousand tons of spinning metal, all alone in the night. It can be a dangerous place, but it's our last best hope for peace. This is the story of last of the Babylon stations. The year is 2258. The name of the place is Babylon 5.
Bought as a costume? It's a plot hole, you're right.
You can easily buy that stuff today. In the future it's probably even easier.