S class is S class...... regardless of any branding added to published fares
I am going by the T&C's on ac.com for the FP in question:
Originally Posted by ac.com
- The Standard fare is composed of the following booking classes, listed from the smallest inventory to the highest inventory: K, A, L, T, S, G, W, V, Q, H, U, and M.
- Flight credit bookings using this Flight Pass are subject to the availability of the Standard S booking class only.