Frankly, I think it’s just an honest mistake. I wouldn’t call it “libshit”. Veganism carries all of the hallmarks of the things I dislike about the Religious Right, religious zeal bleeding into policy decisions until “I think it’s immoral” becomes “the world will fall apart without it”.
I see no difference between that and the “sex before marriage ruins families” attitudes, or some middle-eastern countries’ reasons for banning alcohol. Etc.