ah, good to know. the only account I have currently as preferred is my SO, and he got his cargo holds grandfathered from his month of subscribing. haven't rolled any new characters there since.
Actually, I think the hold itself is unlocked for preferred now that I think about it, unless I unlocked it way back and forgot about it because it was unlocked on new characters back when I was on preferred. Preferred can only buy additional cargo space with cc or unlocks, though.