“For example, the oldest large-scale stretch of ancient surface lies in the Negev Desert. It’s “just” 1.8 million years old—older surfaces are mostly visible in cross section via something like a cliff face or rock cuts. Go back much farther than the Quaternary and everything has been turned over and crushed to dust.”
The article is in no way stating the oldest bit of the Earth's crust is 1.8 million years old. Crust has a specific meaning, the chemically differentiated rocks at the surface i.e. everything but the very very rare bits of exposed mantle. Oldest oceanic crust is <200 Ma, oldest continental crust dates to the Hadean (4.4 Ga, if you set the bar at only zircons).