The dichotomy isn't eating meat vs. not eating meat. It's cruelty vs. kindness. (A vegan may promote cruelty in various ways; an omnivore may promote kindness in various ways.)

The trick isn't to convince the planet to adopt a particular diet; it's to convince the planet to move toward compassion and non-interference. Once we do that, our meal choices are a piece of cake (preferably non-dairy).