It really makes you wonder how the hell they got that far while still believing that the wrong answer could turn you into a fox.
If one's conception of 'the law of causation' is constituted partly by the belief that you can turn into a fox, then it will take a while to figure out that you can talk about the law of causation without believing that you can turn into a fox.
EDIT: made context clearer
I think you're being a bit harsh (I hope out of ignorance). It is a ridiculous belief, yes, and the Zen teachers were perfectly aware of it. If I may quote from the venerable Wumen who compiled The Gateless Gate, specifically his comments on this koan:
`The enlightened man is not subject.' How can this answer make the monk a fox?
`The enlightened man is at one with the law of causation.' How can this answer make the fox emancipated?
From "Hyakujo's Fox", #2 of the 49 koans in The Gateless Gate:
Mumon's poem:
It really makes you wonder how the hell they got that far while still believing that the wrong answer could turn you into a fox.