Xu Tui had been thinking about something while he was searching for Zhao Hailong.
Did the Blue Star have to have internal strife?
Ark's confession should be true. Xu Tui did not kill Ark immediately because he wanted to keep him alive to ask for the reason.
As for showing mercy, that was impossible! Unless Ark jumped out to object the moment Trich secretly ordered a surprise attack on him. Warriors like that needed to be respected. Unfortunately, he did not.
The fact that Ark's confession was true meant that Xu Tui was already on the secret hunting list of the American Sector. It was just like the list that Principal Cai Shaochu had given Xu Tui before they set off. He would kill them if he had the chance.