For me personally: Veganism is also about signaling to the outside world. Suppose I were to skin an animal that died naturally and make a jacket out of it, this would probably be the most ethical way to produce a leather jacket. But I still wouldn't wear it, because by doing so I would signal to the outside world that it's okay to wear the skinned hide of animals. Outsiders can't know under what circumstances I got the leather.

It might be a bit more radical, which is why I might face hostility, but I also throw away non-vegan foods that I unintentionally receive, instead of giving them to non-vegans. Simply because I don't want to project to the outside: "Here you go. I would never eat it because I find it unethical, but if you eat it, then that's okay."