I think Rob is playing the game exquisitely. This is the first time he's played with a HII, which he found, and has managed to keep that fact hidden from everyone ever since as well. He's been able to manipulate people, yet at the same time practically fly under the radar. He came in to this game knowing he'd have the first, and biggest, target on his back, and yet he is still there, with no talk of him ever being voted out by the core group.
I'd say he's playing the game extremely well. He deserves the win this season.