He was really interested in seeing how far she was willing to go for what she came for. His interest wasn't just to mock her.
His suspicion about her purpose became valid when more and more people that he had offended stood up and joined her.
They were just two guys. They flanked her and looked down on him.
One of them said, "He isn't mute. He is just crazy."
This caused all three of them to laugh. But strangely enough, the bystanders that had laughed earlier had become silent now.
They thought what she had said was a harmless jest or even a compliment, so they chuckled. But now they knew that there was something sinister going on, and they didn't want to be a part of it.
They remembered the first and most important rule of the army. They also understood that if this matter escalates, it might lead to the violation of that rule.