In this context, to tell the man not to have sex with the other men in the household/tribe is simply a matter of God making sure to cover all the bases, so that, if God had limited the instruction only to the man not having sex with the women in the household other than his own wife/wives, it would have left the man with a loophole of sorts through which he might try to justify asserting his position as “alpha-male” over the other men by raping them, since he would be unable to do so simply by raping their wives, since God had told him not to do that. The fact that the scripture refers to the man having sex with the wives of his father, uncle, son, etc. as “uncovering your father’s nakedness – it is the nakedness of your mother”, etc., I believe, affirms the fact that the passage deals with an abuse of power that would be meant by the abuser – who is the head of the household and whose authority cannot be questioned without dire consequences – to “put in their place” (under both his power and authority which must necessarily be absolute if he is to bear the responsibility for their wellbeing – which in that culture he was required to bear) all the members of the household by shaming them, if in no other way, and shaming them through – among other things – the use/abuse of his sexual power.