Teenage love does make you retarded. I remember one time sat in a maths lesson, realising my mind was utterly blank except for fireworks and a strong desire to touch every part of a certain girl's body. That relationship went exactly nowhere by the very next day. Anyway, love and adolescence makes you retarded, and Kazoe has taken a strong dose of both.
Also, Hanazono might have realised he is also retarded due to adolescence and love. A bit of luck they have a cute serial masturbator to knock their heads together.