Good Lord! The Smithsonian is a poorly written, liberal piece of c—p. I read that article - mostly disingenuous. They make a big deal of docks, but show only one small dock image while going on with the party line, showing many images which are not relevant, giving short shift to the papyruses guy.
There is no evidence that the Pyramids at Giza were built at any particular time, but there is evidence that they may have been repaired and re-purposed at the time the papyruses were written. Repair and re-purpose of older monuments was common in Old Egypt, how depended who was pharaoh and who was the god ascendant.
The whole timeline presented is based on the two KINGS LIST - the main one is a fake and the other a poor copy. No other dates or modern dating methods are allowed in standard Egyptology. This is the reason the guy with the papyruses wants to stay out of the dating Giza fray.
And see the links at 91 for another opinion by an accredited Egyptian Archaeologist and Science Historian who actually looked at stuff the other guys (the authoritarian traditionalists) - Lehner, Hwass et al - ignore.
Here, from the "poorly written, liberal piece of crap" article is what they, your own expert sources, have to say:
"Experts are thrilled by this trove of papyri. Mark Lehner, the head of Ancient Egypt Research Associates, who has worked on the pyramids and the Sphinx for 40 years, has said it may be as close as he is likely to get to time-traveling back to the age of the pyramid builders. Zahi Hawass, the Egyptian archaeologist, and formerly the chief inspector of the pyramid site and minister of antiquities, says that it is “the greatest discovery in Egypt in the 21st century."
Concerning Lehner, further the article says:
"But the papyri offer important support for a hypothesis that Lehner had been developing for several years--that the ancient Egyptians, masters of canal building, irrigation and otherwise redirecting the Nile to suit their needs, built a major harbor or port near the pyramid complex at Giza. Accordingly, Merer transported the limestone from Tura all the way to Giza by boat. "I think the Egyptians intervened in the flood plain as dramatically as they did on the Giza Plateau," Lehner says, adding: "The Wadi al-Jarf papyri are a major piece in the overall puzzle of the Great Pyramid."
So where do we get the idea that we know who built the great pyramid?
Your own expert sources Lehner and Hawass.
Where do we get the idea that the pyramids were built as tombs?
Your own expert sources Lehner and Hawass.
And your assertion that there are no writing from the time the pyramids were built?
False. They have found them.
But you lean on Lehner and Hawass when it suits your narrative (i.e. how the workers were treated), but when their expertise doesn't suit your narrative, you discount them.
So which is it? Do we know how the workers were treated and therefore know when and why the pyramids were built, or do we not consider Lehner and Hawass as the authority?