As far as radiocarbon goes, samples were taken from more places than just the pyramid of Khufu—and there from multiple locations, between the exposed core blocks (and away from where tourists most usually climb). To explain away the whole of the radiocarbon results by “repairs” would require these “repairs” to account for the entirety of the casing, that part of the masonry most extravagantly praised and entailing all of the problems of raising blocks to the higher levels.
With the Valley Temple (for which read the preceding post), we’re talking about what West and Schoch proposed—which is something very similar, that the entirety of the granite casing is a later addition to a much older building, which either had no casing (so rubbish architecture for the effort) or lost it in the wash.
Image: it’s in the book by Lawton and Ogilvie-Herald. I can’t find one of the relevant location online.