This one is dirt simple: Rule 11.  Every PC I've ever been involved with, on either side of the table, would penalize W and exonerate L.

I don't see how Case 77 applies as a boat can sail at whatever heel angle she pleases.  I.e., heel angle does not have an "equipment in normal position" component. 

Furthermore, a windward boat sailing over a leeward boat must certainly anticipate L "standing up" in her wind shadow (been there!).  In this case, it supposedly happened because of L mishandling the mainsheet.  So what?  What if L had just decided that it's time to sail flat?  Rule 11, Rule 11, Rule11!!!

I’ve heard of that race! Full disclosure, I’m Commodore of the partner club with CYCA, the RYCT. I have long marvelled at the weird start sequence used by the RSHYR. Hardly a typical event and I agree why it’s used in that instance and for the reasons you state. But am I right that you don’t advise a boat that it’s over until some minutes up the course? 

Fair enough.

I'm happy to accept your view then. 

Its clear that the overwhelming opinion opposes John's proposal for whatever reason.

I think the tribe has spoken. 

Thomas ..
  Both Case 77 and Case 91 when taken together imply your answer I think.   Both pertain to the obligations of a keep clear boat when  the equipment of the ROW boat is out of its normal position. 

A boom swinging from the starboard to port side is a boom operating in its normal operating positions.   A KC boat sailing DDW so close along side a ROW boat that if the ROW boat flops her boom over, without ROW changing course, that the boom hits part of the KC boat .. the KC boat has not kept clear IMO.  

In other words, a ROW boat that has to prevent their boom from moving fully to the port side to avoid contact with a KC boat has executed "an avoiding action" IMO.  

I think this is affirmed in the negative when you read the cases I linked to above.  In those cases they discuss the obligations of a KC boat when equipment is or moves out of its normal location.  

IMO, unless there is a case that says otherwise, there should be nothing unexpected about a boat sailing DDW on port-tack flopping her main over such that she is sailing on starboard-tack. A KC should be keeping enough space between them to allow that.

Brad:  I don't think so.  We have established that the boat on the right in the diagram, boat T, is the 'inside' boat.  She is overlapped.  But she is not a right-of-way boat, as she is the windward boat in the overlap with C.  So she must keep clear under 11.  So she doesn't meet the requirements of 18.4  She also has no need to gybe at the mark to sail her proper course.

18.4 typically applies in a situation like the following, where boat A is inside, right-of-way (starboard tack while B is on Port), and overlapped.

Boat A must gybe at the mark to sail her proper course.  She can sail to her proper course, which is the one she would sail in the absence of the other boat in order to sail the course as quickly as possible, but she can sail no farther from the mark than needed to do so.  [See the definition of proper course]  So in this case, she may swing wide, then sail close to the mark as she gybes, and obey 18.4