Extremism of any sort will have its own logical end as evolution deems fit.
It is true that all human beings were at sometime cannibals and continue for longtime to be non-vegetarian on the planet.
Running to scripture for either justifying or debating or denouncing or denying anything by itself is inherently illogical as scriptures were records of moral codes, social rules and regulations, traditions, cultures, entertainments etc practiced several centuries ago.
No scripture is either a panacea or a final authority on anything, much less a comprehensive manual of reference for everything.
Besides, nothing prevents any individual or society from emancipating into a different and better human being or a better civilization-if this term offends some- a different way of living by shedding existing habits and traditions.
But all said and done any activity and every activity need not be politicized and be subject to some bipolar extremism of for and against and carry on in endless debates with in inundation of ancient texts.
It is doing injustice to both the ancient scriptures and the subject at hand and also exposes the inability of human race to view things in contextual relevance and perspective.