So, If you make entry and encounter someone, what do you do with this arm? Do you karate chop him/her? What if he's 10 feet in front of you with a gun pointed at you? Do you shoot from the hip and hope you hit him? or do you swing the weak hand around, quickly establish a two handed grip, and then fire? I cant see the logic with using this technique. Why not maintain a good grip during entry incase you encounter a deadly threat?. It's easy to remove the weak hand to strike or move the bad guy. And if the bad guy happens to be close enough to go for your gun, wouldn't you rather have 2 hands on it then one?
Besides, If the technique is great, why isn't it taught by the professionals?