I think this misses the extent to which a lot of “social grace” doesn’t actually decrease the amount of information conveyed; it’s purely aesthetic — it’s about finding comparatively more pleasant ways to get the point across. You say — well, you say “I think she’s a little out of your league” instead of saying “you’re ugly”. But you expect the ugly man to recognise the script you’re using, and grok that you’re telling him he’s ugly! The same actual, underlying information is conveyed!
The cliché with masters of etiquette is that they can fight subtle duels of implied insults and deferences, all without a clueless shmoe who wandered into the parlour even realising. The kind of politeness that actually impedes transmission of information is a misfire; a blunder. (Though in some cases it’s the person who doesn’t get it who would be considered “to blame”.)
Obviously it’s not always like this. And rationalists might still say “why are we spending all this brainpower encrypting our conversations just so that the other guy can decrypt them again? it’s unnecessary at best”. But I don’t grant your premise that social grace is fundamentally about actual obfuscation rather than pretend-obfuscation.
Most fictional characters are optimised to make for entertaining stories, hence why “generalizing from fictional evidence” is usually a failure-mode. The HPMOR Harry and the Comet King were optimized by two rationalists as examples of rationalist heroes — and are active in allegorical situations engineered to say something that rationalists would find to be “of worth” about real world problems.
They are appealing precisely because they encode assumptions about what a real-world, rationalist “hero” ought to be like. Or at least, that’s the hope. So, they can be pointed to as “theses” about the real world by Yudkowsky and Alexander, no different from blog posts that happen to be written as allegorical stories, and if people found the ideas encoded in those characters more convincing than the ideas encoded in the present April Fools’ Day post, that’s fair enough.
Not necessarily correct on the object-level, but, if it’s wrong, it’s a different kind of error from garden-variety “generalizing from fictional evidence”.