Verse 24:31 tells that women should guard their selves except from the following people:
... husbands, their fathers, their husbands' fathers, their sons, their husbands' sons, their brothers, their brothers' sons, their sisters' sons, their women, that which their right hands possess, or those male attendants having no physical desire, or children who are not yet aware of the private aspects of women.
I interpreted "male attendants having no physical desire" as eunuchs. Is this correct? If so, doesn't allowing them to guard women effectively promote castration? I understand Islam prohibits castration, but allowing them to guard women promotes the eunuch supply chain. For example, I wouldn't buy something that was stolen because I don't want to promote stealing. Perhaps I would be forgiven for buying something I didn't know was stolen, but it's obvious if someone is castrated.