The atmosphere changed when Luke said that the reason was due to the soldiers' glare at Luke. Billy was their current leader, and they respected him, so it was only natural that they would feel pissed. Luke ignored them, though. As far as he was concerned, even if he wasn't a soldier, they were working together and they were on the same rank... if anything, they were below him since they couldn't do something that Luke could.
"All right, my bad," Billy said and then sighed. "I won't refer to your friend as a bird or a monster. Are you happy?"
Luke didn't answer. He just crossed his arms and raised his chin. He could sense the sarcasm in Billy's voice, so he didn't have to play along with it. That made things even awkward, but Billy decided to ignore it once again. His respect for Billy had dropped to zero... he wasn't the same friend of the family.