Para mantê-los longe da tentação.
A resposta curta é que, enquanto a maioria dos soldados no mundo de Game of Thrones parece ser estupradores, os Imaculados não estupram nem saqueiam. Sua castração remove a tentação que poderia impedir sua eficiência. Para uma resposta muito mais detalhada, eu o encaminho para os livros. Todas as citações abaixo são de A Storm of Swords , capítulo 23 (Daenerys), e toda ênfase é minha ..Primeiro Daenerys pergunta ao dono da escravidão exatamente a mesma pergunta que você fez, e ele se esquiva da pergunta gabando-se de que, embora a castração os torne menos strongs, eles compensam isso com sua disciplina:
“Why do you cut them?” she asked Kraznys through the slave girl. “Whole men are stronger than eunuchs, I have always heard.”
“A eunuch who is cut young will never have the brute strength of one of your Westerosi knights, this is true,” said Kraznys mo Nakloz when the question was put to him. “A bull is strong as well, but bulls die every day in the fighting pits. A girl of nine killed one not three days past in Jothiel’s Pit. The Unsullied have something better than strength, tell her. They have discipline. We fight in the fashion of the Old Empire, yes. They are the lockstep legions of Old Ghis come again, absolutely obedient, absolutely loyal, and utterly without fear.”
Mais tarde, na mesma conversa, a pergunta é respondida:
“In Yunkai and Meereen, eunuchs are often made by removing a boy’s testicles, but leaving the penis. Such a creature is infertile, yet often still capable of erection. Only trouble can come of this. We remove the penis as well, leaving nothing. The Unsullied are the purest creatures on the earth.” He gave Dany and Arstan another of his broad white smiles. “I have heard that in the Sunset Kingdoms men take solemn vows to keep chaste and father no children, but live only for their duty. Is it not so?”
“It is,” Arstan said, when the question was put. “There are many such orders. The maesters of the Citadel, the septons and septas who serve the Seven, the silent sisters of the dead, the Kingsguard and the Night’s Watch . . . ”
“Poor things,” growled the slaver, after the translation. “Men were not made to live thus. Their days are a torment of temptation, any fool must see, and no doubt most succumb to their baser selves. Not so our Unsullied. They are wed to their swords in a way that your Sworn Brothers cannot hope to match. No woman can ever tempt them, nor any man.”