As paranoid as I'm sure Bin Laden was, I just can't imagine him staying at one location for two years, unless he thought he was just that secure where he was. And judging by where he was, maybe he felt pretty secure. The other side to that is, if he felt really secure right next door to Pakistan's version of West Point, there was probably a reason.
Bottom line, somebody high up in the Pakistani government knew he was there. He was their dirty little secret. They knew he would hide in Pakistan, but if he was out wandering the mountains, he would get caught. They didn't want him to be caught in their country, so they hid him somewhere that they thought we would never find him. Now that we found their little secret, they don't know what line of bullshit to use.