This isn't supported by evidence enough that Egyptologists or archaeology in general accepts the hypothesis.
If so, it demonstrates that the wood was older. But you must bear in mind the further back in time an object is dated, the more error is introduced into the sample. Off the top of my head, I'm not sure what the error is for the particular Dynasty in question is, I'll have to check some notes. But suffice to say that, even if true, a piece of wood dated prior to Khufu & Khafre would only date the wooden object (a beam, door, post, artifact) and not the pyramid itself. It was common practice to utilize materials from other construction projects, particularly wood, which was in scarce supply.
It makes very little sense at all to those that studied the archaeology of the region and the motif of the sphinx in general, which is one reason why it hasn't been accepted. Moreover, there is no evidence of a pre-Dynastic civilization in the region of the Sphinx & pyramids on the Giza plateau. Besides, Schoch is generally regarded as a kook in the scientific community, not just because of his great antiquity claims of the Sphinx, but also for other wacky ideas that are without genuine scientific support. Many of his methods, in short, are pseudoscientific.
Bauval and Hancock are definitely kooks. They both pretend to conduct science based on preconceived conclusions to which they seek only data that is supportive -even if the data is completely spurious.