I'm pretty sure it's just the taste of meat that the author didn't like. My half-sister don't eat most meat for taste reasons, and the nausea after tasting beef the author describe sound exactly like her reactions.
I once ate a dog meat stew in South Korea. It was tasty, not very different from any other red meat like beef, lamb, or horse, though the spiciness of the stew may have muted any unfamiliar tastes. However, I had to psyche myself up to eat it, and once I was full and my cultural taboos came flooding back I did start to get queasy. There's a significant mental component to what we find appetizing. Most people aren't that far removed from the stereotypical picky eater, myself included, despite having eaten balut, live shrimp, and many other "exotic" foods.