I can see how manhunt 2 being AO is justified. In slasher movies, you are viewing someone else's story. As gory as it is, it's a static rendering. However, Manhunt 2 is just like a slasher film, with the exception of it being your story, and everything being interactive. This is not like the 'cop killing' debacle in San Andreas. That game was about some guy who got screwed by the police, and going through different areas to get lucrative power. You can (and should) go the entire game without so much as collateral damage. The game was not based around cop killing (with the exception of one). Manhunt 2, however, is based around brutal tortures, disturbing images, and murders. It is this kind of game that deserves an AO rating. Not only because of the content, but because of the context. If I was going to compare it to a movie, I wouldn't compare it to a slasher film, but a snuff film.
This is from someone who says San Andreas was just bad enough to get an M rating, hot coffee or not.