This is an example of the (probably universal) human bias that some things, like human lives, are sacred. When we see sacred things treated as even able-to-be-c

This is an example of the (probably universal) human bias that some things, like human lives, are sacred. When we see sacred things treated as even able-to-be-compared to mundane things, flouting their sacredness, it provokes a visceral kind of revulsion, like seeing one's religious icons spat on. Like most biases, this sacredness phenomenon is not all bad; it's an important heuristic allowing us, as it allowed cavepeople, to make complex moral judgments at a moment's notice. But in the modern world, constantly faced with the need to make evolutionarily-strange types of judgments, it's important that we recognize this feeling as what it is: a tool for instantly making reasonably-accurate decisions. Comparing the scale of horse deaths to the scale of human deaths isn't an attack on the value of human life; if the author had to save a human or a horse in a snap decision, I'm sure they'd save the human without thinking. They are not a sociopath with a broken sense of sacredness, they're someone who has learned to do an unnatural thing: put aside their gut instinct and speak rationally about these important issues.