Well, it's the internet, and being what it is, there are no filters and even fewer remedies. Clicking Amazon's "abuse" link apparently does nothing, but prepending the book description may have mitigate the influence. I have also commented on his ridiculous rant, for whatever good that may do.
As for the conversion process, I can't tell you how it was
done. I can tell you how it wasn't
done: It wasn't scanned digitally, that's for sure. Considering that any work Nagel did was prior to 1984, and that he used various analog processes to enlarge and compose images (those are described in the book), my best guess, combined with my interviews, suggest that in all likelihood Nagel used projection
of images on to larger media. From there, it would have been a simple matter of going about creating the different plates as he would have done for any other serigraph.