Maybe he just didn't like being approached by some random person asking if he was a furry? It's kind of a weird thing to just ask someone, though you'd think he'd see it coming wearing a t-shirt like that.
As far as I know, no. I met one in Nintendo World the other day, but I never knew he was a furry until we started talking about interests on Skype when we came back home. He was really friendly too.
Maybe hes dirt poor and got that shirt from good will.
Or maybe Furries killed his wife so now he has a blood lust for them, be he wears the shit as punishment for killing thousands of them in 48AD with his mech-suit "Lantron", hes been on the edge trying to tame his rage, and then you calling him a Furry pushed him over the edge, and those friends of his were the immortal tribe of elders debating on letting him dig up Lantron to let him once again slay the worlds Furries.
Maybe, You've doom'd us all.