I would expect it is very specific to Casey's website, so it would be not so useful for anything else without heavy customization, and at that point you could simply write your own anyways.
I myself use python script to generate static website for me. I have bunch of markdown files which get converted to html and linked together outputting html files. I used to use hugo
which is great, but then decided to write my own. My script is actually pretty short - something around 300 lines.