Contested. It was bought in international waters, but then the offshore border moved. he paid $1 for it.
So the owner is stuck owning something that he needs government permission to access.
Jakes link and others explain it well.
The owner is now motivated to primarily explore the theory that the ship was secretly carrying munitions and that the sinking was somehow justified. I don't think that is his position, but the process to pursue that is pretty destructive to the ship. I think most investigations have concluded by now that it was most likely a boiler explosion that killed her. In addition to the German torpedo.