That is accurate but the highlighted term is not used quite correctly. The "sterile" area is where passengers access aircraft after having gone through TSA controlled/supervised screening. So a pax arriving from a pre-clearance airport arriving at a "normal" gate in the terminal is actually in the sterile area. This is different from a secured area which is an area of airport where specific measures defined in the airport security program are carried out (ie. where access is controlled but persons do not necessarily undergo TSA passenger checkpoint screening before entering). So a sterile area is a secured area but a secured area is not necessarily a sterile area.

The area into which a a non-preclearance international passenger arrives in the US is known as the CBP security zones or security areas (the customs security area and the inspection area). Because these passengers underwent TSA approved/supervised screening before boarding the flight this area is sometimes also referred to as "sterile."