I fail to see the joke, really. I only see false and nonsense statements, which still could be funny or interesting, but I don't see how?
I mean don't get me wrong - sleepsort is intrinsically an extremely funny concept, and I think everyone here gets that. But "constant time" has a rigorous (and pedantic) definition, which sleepsort doesn't meet, so I think for some readers calling it that kills the joke (in the same sort of way that it would kill the joke if TFA's code snippets used lots of invalid syntax).
I like the idea of (ab)using the scheduler to sort numbers.
Now I'm inspired to make my own "sorting" routine, maybe touching filenames and then sorting them with `ls -n`, or rendering triangles and then ripping them off in z-plane order, or stuffing frames into a video and then playing it back.
Haskell's runtime and the OS it executes on exist only as a transient implementation detail of what is, literally, a pure environment!