If you're concerned about this, have you considered opening an issue on the public repository?
Maybe you have some knowledge to share about how to make the site work well with JavaScript disabled?
Maybe you'll find that the team has thought about this, and are planning it?
A cursory look reveals an issue [0] closely related to this, mentioning that there are .html URLs that are supposed to work without JavaScript; that they have at some point verified the functionality with a screen reader; that Google should be able to index the contents; etc.
Maybe that would be a good place to bring up your concerns?
I did. It's literally unusable. I.e., one literally cannot use it in lynx, w3m, Firefox with JavaScript disabled.
As far as I can tell he took 20 years of work and threw it into a garbage disposal.