When I saw the live broadcast yesterday I was sure he would go for the knight sacrifice. And I still think he probably intended to. It is in no way counterintuitive, I think it is rather the obvious candidate for a winning continuation.
But of course a knight is a knight and the queening of one of the white pawns is still some ten moves away. He probably tried to work it out completely to the point where black has to give his rook and the ending is beyond any doubt one hundred percent winning, and after 68 moves of an extremely hard fought game he just couldn't do it.
And in the end, instead of wasting any more time, he decided to play it save. So my take on this is that tiredness and the irrational fear to overlook some miracle save lead to a more practical decision.