This is the weirdest explanation I have ever heard from a Mirzai. Who said having sex is a taboo? Where does it say in the Quran that it is allowed to have sex with the concubines?
Imagine the following scenario: During the war, the non-Muslims captured Muslim men and women, how would you feel if they were to use the women as their concubines, allowing their men to have sex whenever they pleased and the men as slaves?
Our mullahs have translated many words wrongfully, which results in weak-minded people like you who easily get into their trap of nonsense.