Nothing about that not being saved is inexplicable.
The shot was a "knuckle ball" shot which was hit very hard with late swerve.
Do you know how hard those are to save?
Gareth Bale used to score free kicks for fun with this technique, where the ball would enter the goal and you think "that's not even in the corner".
Focusing on the keeper is taking away from the skill and technique of the shot.
It's comparable to cricket where late swing can make a batsman look awful when they handle conventional swing easily.
Very few keepers would have saved that shot. The first 10 yards the ball appears to be going dead straight, where Kinsky was set.
Then the late swerve came into effect.
It's like blaming David James for not moving to Ronaldo's famous freekick v. Portsmouth.