I agree it isn't fair on the DT, but surely for your own match control in a game that's currently a draw, it makes sense to allow it to play out to a more neutral area? Even an attacking throw in before the team has taken it would surely be preferable?
We've now got 2 different posters stating that the whistle was blown when the ball was away from goal, player facing towards the sideline, edge of the PA, but also that the whistle was blown when the ball was in the air (towards goal), and the final blast was with the ball going into the net.
I just wouldn't have expected the second claimed decision from a referee in La Liga, though if RustyRef IS correct, then I can completely understand it.