Rolling wouldn't be a defense to the shoot for many kung fu styles because it prevents the use of effecting striking. For example, that roll prevents the person from throwing an uppercut to the face or an elbow strike to the head. If a person wanted to avoid the shoot with the purpose of striking the face with a fist, knee, or elbow after successfully defending the shoot, then that roll isn't going to be best defense to use to position yourself to follow up with those attacks.I don't know if rolling makes a difference but normally we don't defend double overlooks because you can step out to defend it.