Winds were reported light, but they shifted to favor the reciprocal runway indicating that windshear was lurking. And there's just about always some windshear; so better to have something to give away than be caught short.
Remember the forced landing advice is to aim one third into the field (implied at best glide speed). Aiming for the threshold you better have extra speed.
Really best glide speed is about maximizing field options and applies to still air (a rare and highly localised phenomenon aloft - I have an excellent wind display based on 3D accelerometer and compass sensors integrated with TAS to back this up).
Downwind and a bit slower expands your options. Upwind you will have to fly a bit faster and will not go as far.
Once you do have your field made, it's time to increase speed to have a cushion.