Interestingly the way the author understood the joke with the eggs doesn't speak to well of him: A human can't lay eggs, so the only sensible conclusion is that the deluded person isn't the brother who thinks that he is a chicken but the guy who thinks that a chicken is in fact his brother.

So when he is using the joke to explain that we accept deluded behavior because "we need the eggs", it's in fact him who has a deluded way to think about the situation.