After writing a long article, creating videos, images, and no doubt doing multiple rounds of edits... why should an author also have to ensure that their publication works without JS?
From what I can see, they're doing so codeblocks have proper highlighting but also can be copied & pasted. It's a reasonable choice.
They're not lazy. They even have long, accurate alt tag descriptions for all their images.
If I would guess, they have an inherent desire to see their work viewed in exactly the way it was intended, so they deliberately refuse progressive enhancement when it's a matter of reader choice. The visually impaired who have no choice are accommodated. Anti-JS readers are not.