Mr Koinange apologised Thursday night for the 17 November incident, saying it was the show's last episode on KTN.
He was hosting Miguna Miguna and Esther Passaris, aspirants for the Nairobi governor seat, when the off-air personal attack was made.
Mr Miguna said "Esther is so beautiful everybody wants to rape her".
"You are chasing men all over, nobody wants you," he continued. "You think you're beautiful, you are not. Esther is just colour. Without colour you are nothing."
Ms Passaris, a politician and businesswoman, then accused him of being a racist.