I don't know how many more times I have to explain this, but I'll try and give a comprehensive explanation with no room for misinterpretation. Maybe you can attempt to understand my position instead of just clicking 'dislike' because you don't agree.
As a goalkeeper you have to be the type who comes for everything, or nothing, or your defence will never be sure of what you're going to do. Hart is one who comes for everything. So even if it wasn't the best course of action on this occasion (and it could have been had Nastasic reacted better), Hart has a split second to decide what to do and he is nearly always going to come for balls like that. Most of the time he gets to them first.
Nastasic should know what Hart's style is. Given that Hart is quick off his line in almost every situation, heading it towards the goal in a looping trajectory is pretty much the worst thing Nastasic could have done. Torres was behind him, he could have used his body to shield the ball as it fell and he could have booted it into row Z. Or he could have left it for Hart to deal with, while holding off Torres. He had more time than you imply, and plenty of better options.
I can only imagine that Hart's shaky form has sown seeds of doubt in Nastasic's mind, because a defender who was confident in his goalkeeper would have left it, and a defender who is not confident in his goalkeeper would have smashed it out of play. The only situation in which his course of action was the right one is where you are confident your keeper will stay back. Where Hart is concerned, I don't know how you could be confident of that.