At any rate, our dog sometimes escapes the fence. She is very friendly to humans - lousy watch dog, but will be aggressive to any and all dogs of any size that may pass by. At any rate, someone needs to be at the bus stop these days anyway, and not just for 4 legged critters.
So I would not have been that aggressive about this little dog, but I would have asked them if they had a copy of the restrictions, and asked them to make an extra effort during bus times. My granny said you get more flies with honey, so I'd try the nice approach first. That's just me.
Since I am outside anyway usually, I just go with her if the dogs are out, and chase them away.