Investigating the Iron Plate found in the Great Pyramid - is it legit?

In 1837, a man on Howard Vyse’s expedition at the Great Pyramid of Giza - named J. R. Hill - found a thin iron plate lodged between stones near the opening of the King’s Chamber’s Southern Shaft. This discovery, if contemporary to the building of the pyramids, calls into question what we know about the historical timeline of metalworking. But is there any legitimate evidence for this? And why is this iron plate often omitted from conversations about the Great Pyramid?