The contention is that the sides of the Sphinx at Giza were weathered by rain, meaning it existed originally in a more wet climate than the present day, long ago. A moat around it does not rebut that claim or explain it.
Menkaure is traditionally believed to be youngest. This dating technique can only be analyzed outside of Egypt, but can no longer be done because all scientific dating methods by law must be done in Egypt.
Which does not address how old the Great Pyramid, and the slightly shorter, but equally elevated above sea level, pyramid of Khafre. Stating that the smallest pyramid at Giza is the youngest rather proves the point that largest pyramids are the oldest. This defies human history which documents that smaller buildings and structures like bridges predate large constructions. The latest and greatest technology creates larger constructions, but not with the pyramids of Giza. That is very strange. Still more curious is that the pyramids at Giza are built exactly where the longest latitude of land meets the longest longitude of land on earth:
The implication of this is that whoever built the oldest pyramids at Giza knew this, unless you think that's just a coincidence. The conclusion of many is that the Great pyramids of Giza were built by a more advanced civilization than what followed it in Egypt, which simply tried to imitate it on a smaller scale.