I suspect one reason we see so few Greens up there is that a lot of them were actually out in the world, even during the Schism in the Tower. I'd expect them to be up there with Blues and Reds in being stronger than average.
But then we have more Greens than any other Ajah represented here so it may just be these women were more interested in military pursuit and using the power to fight Tollocs along the blight, not something that really requires massive strength when they are fighting with an army. And perhaps they also travel in groups and just link when necessary. Note that the stronger Greens hung out around the Tower quite a bit