I know a couple of families that have kids under 10, and they're pretty much allowed to play any game, GTA-SA included.
The way they play the said game is just running around stealing and beating cars, beating and shooting people, driving over them... just wrecking havock.
They soon get bored of GTA games though and go play Jak & Daxter, Ratchet & Clank etc..
I think it's because of the language barrier, without sufficient command of english you won't get far in GTA.
...and they're the most polite, well behaving kids I know.... but that must be just bluff, I bet deep inside they're evil-minded killer kids just waiting for the right moment to strike, plotting sinister schemes in their wicked games polluted minds.