Oh, I give the publisher and the Collector the benefit of the doubt and trust them at the demonstrably fine word. But we can never really know for sure.
The Collector has freely published most of these images on his site ... I'm a frequent visitor ... where they've been on display for several years in many cases for anyone to access. Including hundreds of scans of Lincoln film clips that are clearly unrestored - still showing multiple frames and the slots at the sides of the clips - with their current reddish/magenta tint. But those images are a tiny portion of all the prop and costume photos on the site; all free for fans to share - which have never been watermarked or claimed as proprietary.
That's very gracious of you to trust their good word.