The gas pressure acts against the damper rod, if you remove the spring from a shock, back the rebound right off and push the shaft in it will extend again as soon as you take the pressure off the shaft, this is the extension force.
When braking for a turn the forks compress as the weight is transfered to the front of the bike, as the brakes are eased off to enter the turn the front of the bike will lift as the load imposed upon the forks by the cornering forces is not as great as the braking force. The more you can keep the forks compressed through the turn the less trail you have so the bike responds to steering inputs quicker and easier. With the gas forks the extension force was making the forks extend quicker and ride higher when the brakes were released. Increasing the rebound was giving problems in other areas so they are running real long top out springs to hold the forks down in the stroke.