Paris is the exit point of the Schengen area and requires that all passengers have a visa or proof of nationality for the final destination. He most likely had neither.
Noises have consequences.
From EU sio lazima uwe na Visa when coming to Kenya. You can get one on arrival at Jkia. You simply need a ticket and a passport and you're good to land in Kenya.
Miguna was already inside the plane meaning he had already cleared with immigration.