Several minutes ago, while Su Mian was cautiously heading towards him, William's original goal had already been completed. The purpose of creating so many defenses and attacking with the Starmetal Cannon was entirely to split up the group and reduce the number of enemies he had to fight simultaneously.
Of course, that also includes the team with the Array Masters. No matter how he handled Su Mian's three groups, the fourth would either act as a timely reinforcement or deliver a message to their home base. Either way was a bad result for William.
Worse yet, while he wasn't concerned about the Array Masters reverse engineering his amplifiers, William would rather keep their purpose hidden as long as possible.
