Hmmm, well I think a point is being missed here entirely.
Ads are carefully constructed to send a paticular message, and convey a specific impression to a target audience. B.K. Cannon's real age can easily be considered irrelevent compared to how she looked in that Ad. I think the point was to show all differant kinds of people, of diverse age groups, involved. Granted everyone there was clearly an adult, except for her, where she definatly does look quite young, and I think it was intentional since she could be made to look older, or her own age just as well. I think the idea was very much to try and get away with showing a kid playing. Like it or not, kids DO represent a big market share, and while I disagree with criminal action for a number of reasons I've gone into before, there is some truth to there being irresponsibility on the part of gaming companies in their quest to make money. I simply do not believe it's the job of the goverment to correct such things, and if worse comes to worse, just letting things continue is a far lesser evil than censorship.
You get some actor who specializes in playing young roles due to the way they can pull it off (say appearing in high school dramas as a backround character, or occasional bit part for episodes), put them into a commercial doing their thing and looking like they could be 15 or 16, it might not be criminal due to their actual age, but the message is obvious.
Simply put Activision tried to do some subtle marketing to a "taboo audience" here, and got caught because right now a ton of people are paying careful attention to this kind of thing. This wasn't the best time to try something like this.
Such are my thoughts.