Bart, You may find the copyright issue "debatable", but did you go to their website and read it? I appears to be American, hence American copyright law and any relationship it bears to the Berne convention should be known to the owner of this project, and I must assume he is well aware of the copyright status of the materials he is handling and has every good intention to respect potential ownership claims based on this statement on the website:
"Do you recognize someone in the project? Please let us know so we can reconnect them with their lost, but not forgotten images."
To my mind, the real value of bringing this project to our attention lies in its potential historic value, and the rather important technical fact that developing these rolls of film actually yielded usable photographs after seven decades; there would have been none without this contribution. Copyright law and who can claim ownership to what under such conditions is rather complex and usually handled by attorneys who are specialized in that domain, so so I expect if there were issues the owner of the website would know exactly who to contact for dealing with them. He would have every interest in minimizing legal problems, while undertaking a project like this that numerous people could find really valuable.