No idea their reasoning, but if I were a top football, swimmer, or other athlete and knew that a computer could outperform me even at my highest level would be pretty disconcerting.
That's already true of most sports, though. There's plenty of mechanical constructs that can move faster than the fastest human. The challenge is to be the fastest human using nothing but a human body, not to outrun a car or a boat (or even a humanoid running robot, which I assume we could build at this point, if anyone was interested in putting enough money behind it.)
