I've always been under the impression it was S for Scouting, Urban combat and as it is the only ones built with jumpjets, Space.
Most Omnis of the '50s and '60s we're not designed with those until Jihad era.
Pod-mounted was a thing... Officially, one could mount them only if assigned, you couldn't remove something for them. RS and all...
So, yeah...
OTIH, there's : 9 Dire Wolf variants in 3049...
TT