I find the best way to make people realize they are wrong...yorkies do require clothes when it's cold...is to explain why.
All dogs are not the same.
Dogs that don't get cold in cold weather have a double coat. They have an undercoat that keeps them warm in winter. When the weather starts to get warmer, they don't need the undercoat, so they shed it.
Yorkies do not have an undercoat. They are a single coated breed.
Yorkies have hair that is a lot like our own. I tell them I put a coat on my yorkie for the same reason you put a hat on your child.
It doesn't take long to explain and I've never had one person argue further. Whether they just want me to shut up or they realize they don't know what they are talking about, I'm not sure.
Either way, they drop it so I win.
Seriously though, it works.