Sony isn't afraid of marketing. They don't know what marketing is.
They're afraid of the Nintendo fans flaming the game and Sony.
Any exposure tends to be good exposure. Let the Smash die hards cry. They cried when Brawl came out and wasn't up to snuff with Melee. That's what die hards do. As for the more casual market, I don't see them seeing All Stars as anything other than a chance to have a party brawler on their system.