How did Baba recommend using his stories to win arguments and prove the ignorance of others?

The provided texts indicate the opposite of your premise. According to Chapter 2, Baba actively discouraged argumentation, stating, "Where there is a mind for argumentation, there is abundance of ignorance and Maya." He advised his followers, "Do not establish your own side, do not refute the other side, Do not engage in dualistic explanations." The purpose of hearing his stories is not to win debates, but to cultivate personal devotion and faith. As the text from Chapter 2 explains, by listening with true feeling, faith arises, leading to self-experience and a state of happiness, which is the entire goal of the Vedas.