Both of the technicians are correct.
Step-by-step explanation:
The thrust angle is defined as the angle formed by the imaginary line drawn perpendicular to the rear axis center line. It is used in alignment of the four wheels.
It is also used to determine the direction the front wheels are pointing. While the scrub radius is the intersecting point of the vertical center line of front tires with the imaginary line drawn from the steering knuckles.
Thus both the technicians are saying correct. The thrust angle and scrub radius are used to determine the alignment of wheels, if there is any misalignment in wheels then it needs to make it correct to prevent accidents.