[suramya_tomar]

The article specifically says that they "drilled down into the hill and collected core samples that allowed them to use radiocarbon dating techniques to learn the ages of the layers that make up the hill."

They didn't randomly pickup dirt from the base of the pyramid and date it as you seem to be implying, they used the standard method of taking core samples at various depths to find the dates of the various layers of the pyramid. Based on that they made the claim.

[adastra22]

The radiocarbon date of the material used in the construction of the hill doesn’t change when it is pushed around to make a hill. That dirt was already old.