Cows consume carbon (grass, organic matter), produce carbon (methane, other organic matter), and are composed of carbon (more organic matter). Isn't the article espousing placing a carbon tax on a form of carbon?
I wouldn't even single out carbon dioxide per se. If you're going to start an emissions tax and do it right, you might as well target all green house gas emissions and base the tax rate off their global warming potential which takes into account both the energy they absorb and their longevity in the atmosphere.
[0] https://www.epa.gov/ghgemissions/understanding-global-warmin...