Hi Scott,
you wrote: Bauval's argument that the master plan was rigid".
Where do I argue this??...
The discussion/debate over the 10,500 BC date has been raging since 1994, and I really do not want to embark again on this tedious boat-ride yet again. I've made my position clear on numerous occasions (recently here and GHMB as well), so I'll only be very brief here:
In a nutsheel, I firmly believe that the Giza Pyramids are the work of the 4th Dynasty. The shafts are thus part of a construction project implemented in the 4th Dynasty. Thus their astronomical alignments are set for epoch c. 2500 BC.
I nonetheless also believe that the layout plan is based on a sky-model dated to c. 10,500 BC-11,500 BC, with the 'best fit' being c. 11,500 BC (the various arguments for this are in my book The Egypt Code; Century 2006).
There are thus two date incorprated in the architectural plan and design of the Giza necropolis: 11,500 BC and 2500 BC. The relevance of 11,500 BC is given in great detail in The Egypt Code.
So, an in total contradiction to what you say, I do not believe that the Giza design plan was rigidly set in 11,500 BC. Indeed, I do not believe it was set in 11,500 BC in the first place. The design was made in 2500 BC, but with the architect/s deliberately incorporating the two dates expressed (1) 11,500 BC expressed in the layout, and (2) 2500 BC defined by the shafts.
So please cut and paste this above statement everywhere you can, so that I do have to constantly repeat my position on this matter again.
RB