Ahh, I see what you did there, you changed the name of Passive Checks, phb 179, DMG 26, to passive score to make your point.
Yeah, so as you'll see from the rules, a passive check is a check, not a score, and from DMG 26 you can have passive Arcana, along with Dungeoneering, History, Nature etc.
I agree the Intelligence isn't likely to be a strong stat for sorcerer's but like fissionessence mentions, it makes an attractive option for mult-class.
