I hate to spoil the consensus here, if any, but the way I understand it the military games practise communication and cooperation to teach soldiers how to stand up against an enemy in a real world combat situation. Not all the way to being a murder simulator, I agree. But then, it is a combat simulator. Which is still better than than an outright murder simulator. Sort of teach them the theoretical necessities to carry out effective combat. But MH2 is just about thrashing in the most violent of ways whomever is in your way in that game, isn´t it? So that would indeed make it a murder simulator, wouldn´t it?
If I was going to escape from some prison facility, I could be OK with just taking out, or if real need be, killing somebody being a potential witness to my escape, the means of my escape. I wouldn´t need to smash the person up so badly even a coroner couldn´t ID the person.
So I maintain my stance that that game has been made with a story which justifies the conscious act of killing in the most violent ways the opponents in the game. Never because it would be needed. I have seen games where you are supposed to escape from somewhere, and where you just take out the captors one by one through the use of stealth, not savage violence. And by the way, the screams alone from such a killing method would surely attract more problems right away in the way on guards rushing to the scene from all directions. It is just Rockstar´s apparent liking for violence of that level which makes them create a story which justifies the horrendous violence. Something they got infamous for with the GTA games.