Why did Baba insist that only high-caste Brahmins like Radhakrishnabai were allowed to perform the menial service of sweeping his paths?

The source material from Chapter 35 does not state that Baba insisted only high-caste Brahmins could sweep his paths, and in fact, it indicates the opposite. The text mentions that the devotee Balaji Patil Nevasakar performed this daily task first. After him, Radhakrishnabai took up the service, and the text highlights this as remarkable because she, a Brahmin 'worthy of worship by all,' performed what some considered a menial task without any 'dullness of thought.' Furthermore, Chapter 35 clearly states that 'after some time, Abdul moved forward in this' service as well. Therefore, the service of sweeping Baba's paths was performed by multiple devotees from different backgrounds, not exclusively by Brahmins as the question suggests.