MARAGIOGLIO would disagree , although you may be correct in pointing out "absence" of Megalithic construction vis-a-vis the actual Megalithic blocks, Maragioglio's drawings are showing specific locations of what i take to be remnants of a previous construction, the repurposing of past works (blocks of stone) has been well documented , so its quite possible the Mortuary temple was completely picked clean .
Obviously, the MT of Khufu (ATA) has been picked clean. But one must ask oneself, "How did they load those multi ton blocks onto the backs of camels?"
The reason, one would assume, for the megaliths which still remain at the other Giza temples, is that they were simply too massive to remove. Therefore, I would have to disagree with Maragoglio's conclusion about megaliths. However, he may be correct in that the MT was a secondary construction.