"My apologies," Dunn replied politely. "I'll make sure to put it back properly. Let's not make the academicians in the south angry."
At this point, Dunn could roughly guess the identity of the man who reprimanded him. However, he was not very sure yet.
Although he was instructed to flip the book upside down as a signal, someone might rebuked him purely by coincidence. After all, he meets a few people who can't stand seeing things unorganized.
But, there's no need for this man to mention academicians in the south. It seems unnecessary.
To verify his assumptions, Dunn follows suit and mentions the south to see this man's reaction.
The man's approving nod reassured Dunn. He seems satisfied by Dunn's reply. It indicates that their interaction had gone as planned and they share a mutual understanding.
"Yes, that's a good attitude. One should respect the academicians no matter where they are. Those people have contributed a lot to us."