Does it add something to the satire, or does it make it funnier? Clearly the original page's lack of a license didn't make it impossible for anyone else to iterate on it.
And again, I can't stress this enough, the point of the original page was not that every single addition you could make to a website was bad. It was not that you shouldn't have a dark mode. It used radical minimalism to show that by default websites work, even if you have no clue what you're doing.
The lack of niceties is the point. Nobody was unable to read the original page or iterate on it. Could the page have been nicer? Sure. But the point was that even if you did nothing at all, the web still worked.
So it's appropriate in this context, but also pretty easy to argue that 10 lines of code are not a serious copyright threat anyway, and that it's not clear what code on this page is even subject to copyright in the first place, and that the author might have gone all the way and leaned into the fact that you don't really need an entire Git repo with a license for a single HTML page.