I take the commercial in the context of the game itself. I recognize elements in the game that would only ever happen in a game and not the real world. By acknowledging that the two guys in the commercial are just mental-avatars of two guys in the real world playing the game, any real world context can't really be applied because, however "realistic" MW3 is, the game isn't actually realistic.
That being said, I think Grady's point is still valid since my only argument is based on how you take the commercial. In this case, Grady took it as trivializing war, which is extremely and understandably offensive. The way Grady presents his argument shows me he's an intelligent and understanding guy, so I can't call this an overreaction.
This is where the concept of "There's a soldier in all of us" has reached it's limit in appropriateness with people. Last year's Black Ops commercial nailed it:
A group of people from all races, genders, and professions playing what is ever-so-clearly a game of pretend soldier, the game we all played as a kid at some point. The realism of the guns and effects is downplayed by the people holding and using them. No one is being killed because, as I said, this is mostly pretend. The area is undefined and could honestly be anywhere, so any national or political representation is completely absent. There is only one conclusion that can be reached: this is a game. A game that anybody can play. This is really one of the best commercials for a game I've ever seen.
Now, with the current MW3 commercial, they've clearly strained their limits, and backlash is bound to happen. This is something that needed more research on Activision's part. Plain and simple.