Bellamy first names the Knock-Up Stream on-page (Ch. 224 p. 15) precisely to ridicule it.
The payoff
The Knock-Up Stream is the real mechanism that launches the Going Merry to the Sky Island — the villain dismisses the exact phenomenon the plot will validate.
Earliest known caller
(unknown)
Why this matters
A textbook chekhov-explicit / scoffer’s-tell seed: the named mechanism the cynic mocks is the one the plot uses. Pairs with the upward-pointing Log Pose recapped the same chapter. Cross-link Knock-Up Stream.