Reading over the linked page, it appears that the distinction is how much originality there is in the photograph. In this case, it seems clear the museum is jus

Reading over the linked page, it appears that the distinction is how much originality there is in the photograph. In this case, it seems clear the museum is just posting a "mere copy" without any embellishment or artist changes. So I guess I'm with the OP about being unclear what the value of the license is. Oh well, maybe it's just a simple CYA/clarify expectations/whatever.