I fully support Katherine Harris. The picture shows her stirrup leathers way too long for her legs. Her heels should be lower than her ball of her foot. In the current leg position she has on that horse she would end up running her foot through the stirrup. If she is left handed the reins are correct but if she is right handed they are not handled correctly. The observation was made that the horse was not fitted toward Ms. Harris. As to her posture on the horse, it is excellent. Maybe she has been riding her whole life, if the saddle is not fitted correctly to the rider, it is just obvious.
I am not a DU'er, quite the contrary, but am qualified to comment upon one's riding seat.