Then again, he has no difficulty redefining words (such as monogamy) to mean anything he wants them to mean. I don't know why he would bother limiting himself to rigorous logic.
Take it up with dictionary.reference.com I am using their meaning for the word "monogamous": "The practice or condition of having a single sexual partner during a period of time." http://dictionary.reference.com/search?q=monogamous&db=*