This strikes me as an excellent example of ignoring the opponent's threat, making the move you really want to play work. It also shows the acute feeling strong players have for the importance of piece activity relative to material.
As soon as I saw the move on the board, it made perfect sense. But my friend (who is also a master) and I hadn't predicted it while quickly playing through the game solitaire chess. I think this is a perfect example of a strong positional forcing move.