Very bad "book" move in this problem

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Zevras

http://www.chess.com/chessmentor/view_lesson?id=2007

After BxF7+, mentor takes the bishop with the king, which leads to a mate in short order.

Instead playing 1.. kh8, while still a winning posistion for white, allows black to survive to an endgame, which at some stages white has the oppurtunity to screw up.

Houdini 3 evaluates Kxf7 as +15.5, and Kh8 as +2.5