I am no thorpe expert but have seen hundreds if not thousands of pictures of him through the years, just like every one else. Personally I don't think it's him. Again, I am no expert so if it is him then I guess I am wrong. I saw it when it first went up and laughed. Here he is... Shown many times before
I also should add that the provenance the seller gives, very well could be legit, but it just doesn't look like him to me...who knows??
(sorry for the other scans)