Arm, the reason we are talking about the c of g is because any basic textbook on mechanics or physics will tell you that a force applied to an object will move said object relative to its c of g. If the force is applied directly at the c of g then the object will move in a straight line - if the force is offset ie there is a moment arm, then the object will rotate around that same c of g.
When you yaw the aircraft, you apply a force with the TR which is offset a long way from the c of g (any closer and the TR would have to be bigger to compensate for the loss of moment arm - think see saws). Without any further input the fuselage would rotate around its c of g. If you want to turn about the nose or tail, you must apply different forces using cyclic to modify the effect of the TR push and you will succeed when the mix of forces and moments achieves the required turn. But... all the forces you apply to the fuselage will act about the c of g whether or not the resultant manoeuvre is a pitch, roll, or yaw.