Why is the Genesis armed with a manned turret? Wouldn't automated point-defense style systems and countermeasures (chaff, flares, etc) make more sense for ship that is purely defensive in nature?

The current hardpoint is a size 5, which can accommodate a size 4 remote gimbal that will be fired by a gunner station. The Starliner also boast systems like Chaff and Flares for when they are speeding away. The Turret is meant as a deterrent. The pilot/owner can and may hire crew, or have friends man the various stations aboard the ship. The stock model is intended to be defensive.