Why do you need a counter argument? X being valid/true has no impact on whether Y is valid/true. Attack an argument on the merits of the argument, not on the lack of merits of an alternative.

That said, the main argument in favor of eating meat is that humans evolved to eat meat, so our bodies need nutrients that are easier to find in meat (e.g. certain types of protein). However, meat was a much smaller portion of our diets in the past than it is today, so this argument is actually in favor of eating less meat, but still including meat in your diet.

The concepts of veganism aren't really at odds with meat consumption. In many (most?) cases, vegans care most about the ethical treatment of animals (as opposed to vegetarians, who are more often motivated by nutrition), and our current meat processing industry is a lot less ethical than it was hundreds or thousands of years ago when most meat was either free range or wild. So I think it's totally reasonable to take a middle ground and defend meat consumption on nutritional grounds while also defending veganism on ethical grounds.