IMHO, it's more that accepting the consequences of their actions too threatening to their sense of self.
I believe that "live and let live" vs. "there can be only one" is an axis of difference as important as left vs. right or authoritarian vs. libertarian (with which it's weakly correlated). In that context, I'd say there are probably insecure prescriptivists on both sides of this particular fence, riling each other up. "Meat is murder" is the exact mirror image of the Bourdain quote that leads off the column. It's generally not persuasive, and often not meant to be. While it might actually be true in some sense, its purpose is often to demean and demonize those who make a different choice. Just as left and right sometimes forget their principles in their zeal to troll each other, so too do cyclists and car lovers ... or vegans and BBQ lovers. This article is no more than such a salvo.
There are many stupid choices: violent religious extremism, picking altercations with strangers, snakeoil wellness products, driving a giant diesel SUV without a seatbelt, trying to control others online, and listening to The Eagles. Eating meat is just a middling unsustainable practice amongst many. Organized civilization has about another 20-30 years before a cacophony of unsustainable practices brings it all crashing down because there is minimal appetite in enough centers of power for either awareness or reform. The Roman republic/empire is history that is repeating itself slowly.