Would Maz have some sort of ID on him, where he is already a citizen?
To simplify things, if he does not:
He will tell the guards to give him a moment while he "changes" back to his original form. To do this he will go to any dark place nearby (but not back the way he came), and change back into his 'Maz' look. He will then walk out to the guards and say "See? I told you so! Now you recognize me?"
He is still keeping an eye out for any nearby hobogoblins, and will roll a spot check (in next post since this is an edit) and listen to see if he spots/detects any.