https://youtu.be/DaJWEjimeDM?si=rwX4eZZQvGV22iiR first half is citing two guys who think the Sphinx is older than we think (including your guy); third guy and after show that the erosion and the faults didn't come from rain from outside, but water infiltration from below, from before the Sphinx was carved into the rock, and that yes, we do see it in other places in the same rock layer. Other buildings above it don't have that erosion from below. So the erosion is indeed old, but it didn't happen from rain falling after the Sphinx was carved out, so you can't use it to determine when the Sphinx was carved out of the ground.