How did Sai Baba cryptically fulfill his promise to attend Dev's Udyapan, and why did Dev feel deceived?

The narrative in Chapter 40 strongly implies that Sai Baba fulfilled his promise to attend Dev's Udyapan ceremony by appearing in disguise. He came in the form of the Sanyasi, accompanied by two other companions, making a total of three uninvited guests. Instead of revealing Himself, Baba simply asked for a meal, which Dev provided. However, Dev was expecting a direct manifestation or a clear sign and failed to recognize Baba in this humble form. His letter to Jog reveals his profound disappointment; he felt that Baba's word had failed and that he had been deceived because the promised attendance did not result in the spiritual "experience" he had anticipated. He couldn't understand why Baba would fulfill the promise in such an obscure way.