Why couldn't Dev recognize Sai Baba when he showed up as a Sanyasi for the Udyapan feast?

Dev failed to recognize Sai Baba primarily due to the context of the Sanyasi's previous visit. As Dev himself reflected in Chapter 40, the Sanyasi had first come to his house to collect funds for cow protection. This initial meeting happened before Dev had even sent the invitation to Baba for the Udyapan. Consequently, when the same person returned for the meal, Dev's mind fixed on the idea that "He is some guest who has come to get a meal." He admitted that he forgot to pay attention to Baba's specific words about coming with two others. This prior, mundane reason for the Sanyasi's appearance cast a "delusion" over Dev, preventing him from connecting the guest with the divine promise he was awaiting.