> And here is an image of what it would have looked like when
> Belzoni became the first modern explorer to open the lid of
> this granite box in 1818:
Don't you mean "IMO" this is what is would have looked like as Belzoni did not describe what you have envisioned here? And again, no "he did not open the lid of this granite box" nor is there any reason to believe he was the "first" to do so in modern times implying what he found was "undisturbed" i.e. "original" to the sarcophagus.
Belzoni did not say it was "filled" with earth and stone, but rather that it contained a "great quantity" of this material. As compared to what? Nothing? He also said "the lid had been broken at the side, so that the sarcophagus was half open". No where does he say he had to remove the lid to look inside implying there was no need as it was already "half open" anyways. He does not notice the bones among the "rubbish" until the next day implying they are quite small to be "bull bones". Interestingly, he then goes to look around the chamber for inscriptions which he finds the walls covered in Arabic writing, among possibly others, meaning obviously the place was well visited before him.
The next day a gentleman Pieri came with him in which having "rummaged through the rubbish" found several pieces of bone which he claims were later sent to London and "proved" to be those of a bull, but this is not been verified since. Could be chicken bones for all we know.
So, what he found in his own words was a "great quantity" of "rubbish", or as we Americans call it-"trash", filled with dirt, stones, and several pieces of bone which apparently were not that large as expected from a bull as he didn't even notice them the first time he looked and were only discovered by "rummaging" through the "rubbish". He found the lid broken and the "stone box" half way open and makes no mention of having to remove it. He finds numerous Arabic writing among others giving the clear impression G2 had been breached in antiquity more times than a $7 whore. There is literally nothing to suggest what was in the stone box was original if only to the contrary. Your interpretation of Belzoni's remarks seems quite at odds with what he actually says.