The Chiefs only came out ahead if the Bills would have came back and won the game. I tend to think that the Bengals would have won, they were ahead, driving when the injury occurred and were at home. Cincinnati wins that game, then KC is hosting all the way through.
The only thing that worked in the Chiefs favor is that the Bills and Bengals have to play each other, while KC gets the lowest seed, for their first round game. But if the game had been replayed and the Bengals won, that still would have occurred.