I'm only part-way through the decision, but it doesn't appear to have anything at all to do with making API calls; rather, it has to do with Google incorporating implementing API code from Java into Android.

In other words: Google wasn't merely calling a Java method using Java's API (e.g. max( $var1, $var2 )); rather, Google actually copied the code to implement its own max() method.

Basically: Google didn't want to open-source its own code (so it couldn't utilize the Oracle GPL license for the APIs) and didn't want to ensure interoperability with the JavaVM (so it couldn't get certification to use Oracle's commercial license) - so Google instead just copied the Java API code and incorporated it wholesale into Android, as Android APIs.

To make a WordPress analogy: this case appears quite similar to Thesis 1.8, which had to be rewritten because it was found to have incorporated core WordPress implementing code.

This decision, and Automattic's subsequent announcement, are indeed interesting; in part, because what courts consider to be "APIs" and what developers consider to be "APIs" aren't necessarily the same thing.