I think they didn't call it a 32 for the same reasons Federal named their revolver cartridge the 327 Federal instead of the Federal 32 Magnum.

When people hear 32 they think of weak, old and obsolete cartridges that are not a good choice for self defense. Using 30 SC avoids the stigma of 32.

Calling it a 30 helps it stand out from the crowd of other cartridges with 32 in their name. You don't see much 32 ammo on store shelves but if they had called it a 32 SC it would have blended in with 32 ACP, S&W, S&W Long and H&R magnum.

It also reduces the chance of someone going to a store and walking out with the wrong ammo.