I'm not sure it's actually supposed to be surprising that the Judge came down on this side. The whole point of the Judge/Jury separation is that one gets to decide matters of law and the other matters of fact. Clearly whether or not the doctrine of copyright extends to the expression of an API is not a fact being contested here.
The more amusing bit is that the incriminating code snipped in Oracle's slides goes the other way: the code is in Java because Josh Bloch (the Google employee who checked it into Android) wrote it in the first place and gave it to Sun. So the same TimSort implementation got carried with him into Android. There may still be a copyright question if he actually assigned ownership to Sun, I guess. But suing the author over the use of open source code he gave you in another open source project is... yeah.
The more amusing bit is that the incriminating code snipped in Oracle's slides goes the other way: the code is in Java because Josh Bloch (the Google employee who checked it into Android) wrote it in the first place and gave it to Sun. So the same TimSort implementation got carried with him into Android. There may still be a copyright question if he actually assigned ownership to Sun, I guess. But suing the author over the use of open source code he gave you in another open source project is... yeah.