This article conflates two important issues
There are two distinct issues in this case and they have very different results for the FLOSS community.
1. Is and API itself copyrightable
An API is how other programs interface with your software. The people writing that code, as far as I am concerned, are users of your software. Hence the API is the user interface. Copyright doesn't extend to user interfaces as was decided in the case Lotus v. Borland. If the court rules against Google this then this is devastating for open source efforts to duplicate the functionality of propriety software while maintaining compatibility.
2. Direct copying of code sections:
IF it is clear that google did copy the Java source code then this article is correct. THEN result for FLOSS should rule in Oracles favour, as we need to be able to protect our source for the GPL to be powerful. It is a big IF and a big THEN and I admit I haven't delved into the code, but a cursory glance at the example seem to point to code stealing as all the private variable have identical names.
So as long as the court decides that an API is a user interface and copyright doesn't extend to it, this becomes just a code stealing case. I am disappointed that the API distinction is largely glossed over in this piece.