How does the story of the Malegaon doctor's nephew illustrate the power of Sai Baba's Udi?

The story serves as a powerful illustration of Udi's glory, as explained in Chapter 34. The ailment, a bone-cyst, is specifically described as a "most difficult and extraordinary malady" that resisted all conventional treatments, including efforts by "expert and intelligent surgeons." The complete failure of medical science is contrasted with the simple yet divine remedy offered by Sai Baba. The family's faith was that if Baba applied Udi, even incurable diseases would perish. Baba's instruction to simply "smear it on that wound" demonstrates that the Udi's power is not medicinal in a conventional sense but spiritual, capable of succeeding where all other efforts have been exhausted.