Oh that's for the intake manifold. The purge valve is only being replaced because it is affected by the intake manifold modification.
The recall says nothing about a catalytic, so if you have any future problems with that, it would be a regular warranty item. The factory would never pay the dealer for a pre-emptive repair. It would require the dealer to have been authorized by the factory to replace any part.
This is what it says:
2006 - 2007MY Impreza and Forester 2.5L NA
Intake Manifold Modification
The purpose of this bulletin is to inform you of a modification which was made to the intake manifold.
The boss and tie clip that secured the engine harness to the intake
manifold was removed. In addition, on Forester models the mounting
position of the purge control solenoid valve bracket was slightly moved
to the right. Due to the modification the shape of the bracket was
changed. Therefore, if the intake manifold is replaced, the purge
control solenoid valve will also need to be replaced."