I think you're mixing up intellectualism and morality. There are many reasons people choose not to eat meat, and some of those reasons are emotional or moral rather than intellectual. Some people only eat a vegan diet because their doctor told them they had to. Are those people somehow more intellectual than someone who researched the science and came to the conclusion that humans are omnivores?

You have already judged the outcomes of people's decisions as being objectively correct or incorrect. To you, eating meat is incorrect regardless of the reasons for doing so. That is not an intellectual stance, it is a moral one. You are ultimately judging people for having different values than you. Maybe they don't care about the environment, maybe they don't care about the safety of animals or other people. Like it or not, to care about those things is emotion. You can argue they're wrong as much as you like, but you can't prove that any human behavior is objectively "the right thing to do," meaning you are not as objectively correct as you think you are. There isn't a one-fits-all solution for how to live. The sooner you realize that, the sooner you can stop judging others for not being like you.