If you don't understand the code, probably you don't know what kinds of mental processes are needed to understand it. Maybe "recalling almost instantly infernally long minutiae of details" isn't actually among them. Maybe great intelligence isn't, either.
There's a whole genre on YouTube of videos of people doing day-to-day work with skills that seem utterly superhuman, with names like "Fast Workers #230" and "People are AWESOME 2020", like https://youtu.be/YmkPoiEcgJM. Actually, though, if you practice almost any skill every day for an hour or more, working diligently to improve, after 20–40 years your ability at it will seem superhuman, even if you're average intelligence or slightly below. (Unless it's a professional sport, in which case people will be mentally comparing you to Lionel Messi or Tiger Woods, and you won't get that good. Or a popular hobby like knitting.)
It definitely does not require 20–40 years of effort to understand quantum physics or code written in K.
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Now, suppose that it were true that reading poetry written in Volapuk (or whatever) were a niche interest because of some essential feature of Volapuk that inherently limits it to a small group, rather than because learning Volapuk takes time that most people haven't put in, for the standard diffusion-of-innovations reasons. Would that be bad? Would it mean that people writing poetry in Volapuk had an "utter inability to 'read the room'"?
I don't think so—to attribute their choice to do so to such a cognitive handicap, you are presupposing that you understand their motivations, and that those motivations include maximizing the popularity of their creation.
But it should be obvious upon a moment's thought that plenty of poetry, and code, is written with no thought for participating in such popularity contests; it's written for an audience of one, or two, or forty-eight. Perhaps the majority of poetry and code. So writing it in Volapuk, or K, may actually be a rational strategy if it appeals to your intended audience—not an error resulting from a mental disability, as you claim.
More generally, quoting Chip Salzenberg:
> It's usually a big mistake to assume that a number of experts on a given subject disagree with you because they don't grasp the true situation.
(cf. http://canonical.org/~kragen/quotes.txt)