All we know for facts is the scooter was behind the skateboard, could have been in the middle of the lane and not directly behind preparing to overtake, anything really. We then know the skateboard "flipped", so could have gone directly backward, sideways, or at any angle between them. We also know the skateboarder wasn't in control of the board. Not long ago there was a phase when I went past a lad every day, presumably on his way to school, on a unicycle. The situation described by the OP was one I dreaded every day and I sympathise with the scooter rider.