First of all, I don't believe that Russ Grimm has turned down an interview with the Bills. He was preparing for a playoff game, what do you expect him to say. This will likely be his one and only chance to be an NFL head coach. When Kurt Warner retires, Grimm's stock will drop faster than the Cardinals offense. In the NFL you need to strike while your hot. This is as hot as he will ever be.
However, he is not qualified to be an NFL coach. He is not the Offensive Coordinator of the Cardinals. He is the Running Game Coordinator and Offensive Line Coach. The Cardinals have a Passing Game Coordinator. In addition, Ken Whisenhut calls the offensive plays. This means that Grimm has never even been an Offensive Coordinator. He has never called offensive plays in a game.
He would be a good Offensive Line Coach or Offensive Coordinator, but not qualified to be the Bills head coach. Let's hope the Bills do not bring in an unqualified head coach like Grimm