Seeing the battlefield stabilized, the two sisters mostly held back their efforts. After all, such battles didn't benefit them; killing excessively would only waste their energy. It was better to allow these people to feel gratified for a while.
Having packed up his stuff, Du You left with the sisters. Now he had confirmed that the enemy's warship truly had no energy and wouldn't attack him, otherwise, he wouldn't have ventured out randomly.
Du You didn't use himself as a lab rat; he ventured out because he noticed that the Warship Commander had come out, and since he was not attacked, Du You assuredly wouldn't be either. He came before the warship and saw the Demon Extermination Spirit commence its attack on the warship's main gates.