I think absence is the wrong word. Moss was not absent. He was very much part of the offense during the post season. Serving as a decoy, taking on double/triple/multiple coverage, downfield blocking, are all specific and important roles on the offense. What you're looking for is something to describe the lack of targets to him. Lack of targets <> absence.
Assuming that's what you meant, so I think it's ultimately on the opposing defense, because the Pats take what they are given. You can script as many plays to Moss if you want, but in the end, if the opposing team is determined not to give it to you, they won't. In the games leading to the SB, Jax and SD gave them Maroney and the short passing game because they were determined not to let Moss beat them. In the SB, the Giants gave them a little bit of Moss. Enough for him to make some catches and score.