i suppose a quick test would be getting the model to write down Micken's essay end to end.
if the original essay was stuffed within the prompt window. the result will be word accurate.
unless this is a model trained specifically on Micken's essay (which claude is not).
Didn't we get this with Harry Potter back in like gpt3.5? I'm sure I saw some news about it, someone getting it to output a book's intro word by word, couple pages?
This seems like a classic case of doing it being proof that it can happen, but not doing it being insufficient proof that it's impossible. I don't think there's a "quick test" of whether there might be a more effective prompt that would cause it to reproduce more effectively.