I wholeheartedly agree. The hypothesis has the advantage in being 100 percent compatible with all the other serious hypotheses that are out there, and a number of the ones that are hard to take seriously.
I found out about JD's book way back when from the late William Corliss (a kind and patient correspondent, for which I'm grateful) wrote about in his Science Frontiers newsletter and gift shop. The way he had his avocation figured out, I wonder what heights he might have hit in the internet era.
Wow, the hieroglyphs list emphasizes why ‘words’ need to be understood in context! So many of the images are so similar that context yields meaning.