You may be correct about that (I eventually decided the topic was too complicated for most people to figure out and disengaged with it). But the argument you present is slightly different and more nuanced than "cows drink a lot of water, we should use that water to grow soybeans instead". There are other solutions if you accept those conditions like "figure out how to get incentivize importing feed from places without drought conditions instead of growing alfalfa during a water shortage" and "figure out how to encourage more pasture-raised cattle farming on un-irrigated pastures". The point is that the extra facts (feed can be imported, cattle farming is possible in some place using minimal irrigation, not everywhere has droughts, water is used in alfalfa farming) change the initial A->B->C logic to A->D->E->C, and maybe there's an A->D->E->F argument that you miss if you don't know that D and E exists (and maybe F is more sound than C, or even directly challenges it). That's kind of the point of the original article.