"What's your name? Where are you from?"
"Nolan and this is my elder brother, Buenos. We come from Icebound Town."
Negan Murray answered the guard's questions smoothly.
Before arriving at Sedimentation Bay, the two had asked around and learned that it was best to tell the truth to the guards of Graycastle to avoid encountering problems upon arriving south. But they never planned to visit Graycastle.
Once through Cage Mountain, they would arrive in Kingdom of Dawn's territory with a vast hamlet to take refuge in. Relying on their combat experience, the two had no worries for their future.
Thus compared to nobles, disguising as common folk made them less conspicuous.