A clumsy move, completely missing Black's reply. As a result Black's concept is an immediate success. 19.Kh1 or 19.Nc3 are better alternatives.
The queen is heading for the a7 -g 1 diagonal where she can exercise her long-distance power. Just as it helps when the third rank is available for a developing rook, here the diagonal is open and available. This maneuver is quite familiar in the King's Indian.
With the previous example in mind, the intentions behind this little move should be obvious now.
This maneuver is typical of the sort of Pirc position which arose in Bryne-McShane, Malmo 2003 . In that case the (almost forced) queen transfer from the d-file was less successful.
Here White was not so much aiming for the a2-g8 diagonal, but for a more active location for the queen in general.
The liquidation of central pawns and rooks has led to a symmetrical pawn structure, but White still has some pressure with his pair of bishops. He managed to turn his advantage into a win.