People on the autism spectrum can get really absorbed by their special interests. It seems that this Greek man suffered a brief delusion (being owner of all those ships). Delusions are not part of autism, but the way he categorized the ships and took care of the entries is reminiscent of autistic exhaustive or meticulous behavior.

About the hobbies, not every hobby is a sign of ASD, but there are hobbies that have a bigger proportion of autistic individuals compared to others. Collecting trains has become a meme and a stereotype, but there are others. If you see someone with a train collection, they are not necessarily autistic, of course. But if they have a train collection, records of every change within the collection, books about the hobby, etc., you'd have the right to be suspicious.

Disclaimer: I speak from my experience with loved ones with ASD. I hope I'm not misrepresenting anything.