The leather is a product, not a byproduct, just not the sole product. I fail to see the logic that killing a mink for its fur is wrong, but killing a cow is okay because we get meat along with the leather. You can also make arguments about how it’s okay because cows are raised specifically to be killed, but the fact remains that we kill orders of magnitude more cows than we ever have minks. My previous argument stands unchanged about how protesting mink is a small victory and most animal rights protesters stopped short of going for a big one.

Btw, I’m not an animal rights protester, I eat meat and have leather furniture. I’m just backing up the top level argument that Yale students aren’t protesting the big stuff.