Yeah, that was the flaw at the time, it wasn't in the book and not thought to be needed in the book.

I'm reading a book at the moment (https://academic.oup.com/book/32137) in which the author makes a point of the distinction between "the goals of a game and our purpose in playing a game". My purpose in playing games is never winning for winning's sake, let alone winning at the cost of violating basic decency. But sometimes the purpose is best served by pursuing the goals quite single-mindedly. Competition can be fun, and some games become much more interesting when both players are really trying to win, even when this means using 'cheap' moves, learning to counter the cheap moves, etc. There's no reason this approach has to carry over into the rest of our lives; we can 'play to win' in the appropriate arenas while caring deeply about courtesy and ethics.

I understand this attitude, but I think the line between tactical progress and (the bad kind of) exploiting the rules can get very fuzzy. It's arguably more interesting to do whatever the game allows, even if it seems cheap, and find out the hard way whether there are ways to counter it. Sometimes there aren't, or the counter-tactics just leave you with a more boring game (usually fixable with rule changes). But sometimes you can uncover hidden depths this way, and the opposite approach can leave a game very tactically stagnant.

(I'm of course not suggesting this was the Chappells' direct motive, or even that this incident realistically could have uncovered hidden depths in the game of cricket. But as a general philosophy I think 'playing to win' has some merit, even from a perspective that ultimately cares about the health of the game and not just about winning as a terminal goal.)