It sounds like the doctor is telling you that you already have CCW to the maxilla. That is to say, your occlusal plane angulation is very much near what someone with a HIGHER inclination of the OP would have a CCW rotation to ACHIEVE. It's also common for people with a class 3 type relationship to have an OP that is 'too flat'. Looking at the diagram, your OP does appear LESS than the norm and NOT the type of OP one does CCW on. Also, appears to be 3 molars in the diagram. If the 3rd one in the back is the wisdom tooth, that can preclude a BSSO.
Not doing CCW to the maxilla on someone who's OP is 'too FLAT' to begin with does NOT PRECLUDE the mandible from swinging UP and FORWARD (CCW) when a retrusive maxilla is displaced UP and FORWARD. On the contrary. YOur mandible would swing CCW up and forward with the proposed displacements to the maxilla which would tend towards relieving part of the lower airway.
The situation is not too different from a SINGLE jaw surgery to the maxilla where someone with a very HIGH angled OP, has the OP reduced and maxilla advanced to affect a CCW AUTO-ROTATION of the mandible. Except in your case, since they can't reduce the inclination angle of the OP since it's already low, they need to remove an 'even' section of it to move the whole thing up and then move that whole thing forward.
ETA: correction
