I mentioned it in my post: in Image Capture, select the “Virtual Scanner II” device if it exists, and in the Details, set the Media to “Document” and Media DPI to “72 DPI.” You should see the preview of the first page of the Bitcoin paper. But that's only possible if the virtual device exists, and it's still unclear why it's hidden for some people but not others.
Huh. So I had a "Virtual Scanner" but not "Virtual Scanner II" when I was seeing the Treasure Island picture as a preview, but then after like a minute of doing other stuff I went back to Image Capture and it was gone and I couldn't get it back.
