Dynamic Soaring depends on crossing wind gradients. This guy's theory is about "dynamic soaring" without crossing wind gradients.
Second paragraph from the top.
In the windward turn, the albatross maintains height and loses momentum due to the unbalanced drag force. The loss of momentum is seen as a loss of ground-speed rather than a loss of airspeed. Airspeed is constant because the tendency to lose airspeed due to drag is balanced by the tendency to gain airspeed from the increasing headwind components, whilst turning relative to the wind.
As someone else remarked, the opposite of the "downwind turn". If you start with the belief that you can gain airspeed by turning from crosswind to upwind, you know that everything which follows is nonsense.