Satan agrees with vegans and vegetarians on one of their chief arguments: it is less expensive—both financially and ecologically—to live on plant matter than on meat, even if accounting for the required haulage of seasonal products that were generally unavailable a century ago in order to satisfy the nutritional needs of a human being. The Devil does not wish to discuss obviously untenable or plainly stupid arguments; for example, there is no reason to debate that Man is biologically an omnivore not a herbivore.
Yet agreement is one thing, caring is another. The latter turns the ecological fact into a moral question, and the Devil asks His followers a few rhetorical questions: are humans unconcerned about the future for vast population groups including their own? Are humans willing to live on a polluted planet, and can they look themselves in the eyes knowing they leave an exhausted Earth to their offspring? Do humans believe that a reduced production of meat should be permitted? The vegan answer is no, and disagreement with them is impossible without either being ignorant or feeling guilty. (The latter option being reserved for humans, of course, as Satan has no idea what it means.)
But, acknowledging the validity of one moral argument is a slippery slope, and allows the vegans to present another moral argument, which is perhaps their primary argument: how can humans, living and feeling beings, justify killing and devouring other living and feeling beings? Why do humans find it dandy to eat cows but not each other?
Meat eaters sometimes argue that other carnivores and omnivores usually have preferences, too, and usually do not eat their own species; however, this does not necessarily apply to humans, who might be one of several exceptions. Humans have eaten only certain species for as long as we can remember but that is a naturalistic argument, and vegans are correct when they state that humans have the capacity to make a choice, as humans have done in other areas of their biological history; for example, when they take medicine.
Humans who eat the flesh of other beings genuinely have some explaining to do: they do not have to kill animals for food. They choose to do it, and it changes nothing trying to justify the killings by peeping that the animals maybe individually and most likely as a species would meet their destiny more brutally in the fierce struggle for survival in Nature. At best, humans can patch their guilty conscience by killing their prey “humanely” (which Satan thinks sounds a little disturbing, because it reveals human standards for killing each other in cold blood), and thus flaunt your hypocrisy by wanting the dead animals on the one hand but feeling uncomfortable killing them on the other. Vegans see through this hypocrisy and stress that humans do not escape their choice by pretending to be friendly executioners.
Killing animals for food is perfectly legal, and like the ecological view it is a moral choice. It is unnecessary; it is impossible to pretend otherwise. Satan thinks it would behoove His meat-eating followers to admit that they kill intentionally and harm the planet merely to satisfy their own culinary pleasure. Satan does not personally care what humans eat, however. He is the Devourer of Souls and would never lower Himself to consuming the improper foods of humans.