You have to admit, though, that's it's pretty galling of Google to process source files and strip copyright statements! And while it's inevitable for lawyers and legal professors who aren't also programmers to get some of their facts wrong, the arguments occurring in the legal sphere aren't "bullshit." Google is definitely rocking the boat, and you have to ask yourself which is better for the GPL--a state of legal uncertainty or of certainty. The answer is far from clear.
Here's the problem as far as I see it. While it might seem clear to us that a user-land program compiled against GPL'd kernel headers is not derivative, that will not be the question that goes to court (if this issue goes to court). The question that will go to court is, are Google's processed headers derivative of the unprocessed headers? That question is much closer, and if it comes out that they are derivative, it means that it's more likely that the first question will be answered that user-land programs are derivative. The outcome of this case would change the course of the law in an unexpected way.
And the fact that Google is running a simple program to mechanically process those headers... that's not the best case for a defendant to carry into court. It's one thing to re-create those headers by hand, it's another to mechanically transform them, the legal theory of derivative works notwithstanding.