Their explanation that the speedup comes from the task changing from a catching task which requires higher brain functions to a simpler visually guided pointing

Their explanation that the speedup comes from the task changing from a catching task which requires higher brain functions to a simpler visually guided pointing task seems strange in this regard. As you say the catching point doesn't have an ETA. To catch the ball without knowing when it hits, you would naturally move as fast as possible. If there's a trajectory or the real ball, you have more time and can react slower.