There is absolutely no need to invoke asteroids hitting (allegedly) the region in circa. 2200 B.C.
As the GP was allegedly (Scott implies?) not emptied of its food contents until this time, one has to wonder how the stuff managed to avoid deterioration for some 300 to 400 years - especially when one looks at the science and technology we today use to store seeds, etc, for future generations.
The more one digs into your theory, Scott, the more improbable it becomes.
However, and in all fairness, much the same can be said about the majority of theories about the pyramids - the Great Pyramid in particular.
So few answers - and not one of them mine.