This isn't the US version. It's the International version. Unlike, say, the censorship for the Elin or Mugen Souls, the uncensored Sentinel would be dangerously close to qualifying as child pornography by the standards of, say, Canada or Germany, where the law includes so-called "simulated child pornography" as banned. I don't like the censorship, but they really didn't have a whole lot of choice here. It was either censorship, or IP ban anyone from Canada, Germany, and I don't know where else to cover their asses legally.
And no, just saying she's of age (which they already do) wouldn't cover it. Such laws tend to go more by appearance than stated age.