The OP was confident and comfortable in the actions the OP was taking and the OP has extensive experience of that road at (ahem) rush hour and had the OP acted as the respondent suggests, the OP could well have found himself responsible for a multiple vehicle collision with scope for injuries to persons the OP knows in real life and faces/cars he regularly sees and acknowledges on this commute route, even a minor collision would likely engender significant road blockage, none of which the OP would want. To engineer such a conversation the OP would have had to stop the driver in the carriageway, which is not an option for the above reasons, however polite the OP may have been. The OP has clearly described it as narrow and wind-y, an opinion backed up by a fellow rider already in this thread who is clearly well aware of this stretch and equally comfortable asserting their own safety against a rare case of motorised bully on roads that bear no resemblance to the guides busways of Cambridge.