I have, wear and enjoy several fur coats. (All re-sale finds, by the way...not that it's really necessary to qualify.) Though there may be the occasional, unsolicited opinion from others, no one has ever been quite so demonstrative about their objections, as the person your friend experienced.
It is highly inappropriate to behave the way this person did in accosting your friend. In fact, any unsolicited comment at all, would have been inappropriate. Even a solicited one should be given with some modicum of grace and tact.
As another poster said, the animal has been dead for however many years. No amount of NOT wearing the coat is going to bring the creature back.
To me, wearing the furs I have and enjoying them, is more of an honor to the creature that lost it's life, than throwing it in a pile of rags, because I may disagree that it had to die in the first place. I didn't kill it all those years ago. Nor did I have anything to do with those who took it's little life, in pursuit of their own comfort.
But I am grateful for the sacrifice it made to ultimately bring me warmth and comfort. So in honor of that, I wear the darned thing...and yes, am nice and toasty.
Other people need to mind their own business and sew their lips shut!