In the ST16S always prevails the control of the sticks to DataPilot. So when it fails, you don't lose control of the drone. The fact that DataPilot has to be turned off is so as not to interfere with UgCS commands, it makes a lot of sense. But the ST16S apart from a ground station is the controller at the same time. You remove the part of the ground station that becomes the UgCS and you keep the controller.
Let's remember that the concept of ground station and controller in the same device is a "relatively" new concept, all integrated in one, but a laptop has always been used through a telemetry connection to establish the connection with the ground station installed in the laptop.