you're wrong.
The rule states that when the QB slides FEET FIRST, the spot is where the slide BEGAN.
I know the play you are talking about. The Wife asked the same thing and she knows nothing about football.
Exactly, look at the tape. He did not slide feet first and his elbow touched the ground first...which is where the first ref indicated...but when the ball was moved and spotted, the other ref he tossed it to moved it back at least a foot.
Bingo.