It’s in the headline of the article; because he thought that he was associated with the ultranationalism Grey Wolves association. So purely because of the costume resembling an ultranationalist group, being a grey wolf.

It’s like punching a guy for wearing a white hooded costume around because they look like the KKK but really it was just a guy in costume for his favorite niche community, the pointy hood bakers or something. Not saying it isn’t stupid but if you dont know what furries are and have the association of that group in your head I can see it happening. It obviously shouldn’t, though.