I don't see the problem. Sure-in a vegan restaurant, there are more likely to be people who are horrified by it than others. And I would say that wearing fur is pretty tone deaf. Honestly, though, I have to wonder how someone in the restaurant at that moment (as opposed to the press who can go home and look it up) would know it wasn't faux as opposed to natural fur. But unless the restaurant has set a dress code that she is violating, it is no more rude than going to an all-organic restaurant wearing clothing with man-made fibers or non-natural dyes.
I eat at a vegan restaurant occasionally. It is along one of my favorite motorcycle rides. Last time I was there, the waitress asked me a lot of questions. About my motorcycle, how/when I learned to ride, how my family and friends reacted, and a dozen or so more similar questions. They weren't busy, I was alone and she doesn't know any women riders, so she asked if she could talk to me about it as she was interested in riding. She didn't ask me even once about my leather boots, chaps or gloves. I usually am not the only biker-and they certainly don't seem to be offended by the biker business (which means lots of leather) they pick up.
And their grilled portobello sandwich is wonderful. I would be very sad if the decided to set a dress code that disallowed me from going, but until and unless they do, I will continue to go there even wearing my decidedly non-vegan motorcycle apparel.