What is ironic about Mr. Avery’s allusion to the Rosetta Stone? How does Scout show that she does not know Mr. Avery’s purpose for using this allusion?

In chapter 8 Mr. Avery thinks his prophesy about seasons changing when kids are bad comes true. He thinks it was written on the Rosetta Stone that kids being bad meant changing seasons. Scout answers,  "I did not wonder where Mr. Avery gathered his meteorological statistics: they came straight from the Rosetta Stone." Scout clearly misunderstood the origins of the first form of writing.