Agreed. The maintainer can insist on writing the code that makes it into the kernel for quality purposes - that makes sense. But here the article author is a co-author of that patch.

In academic publishing, this is analogous to sending a pre-print to someone, and that person then publishing on that topic listing you in acknowledgments rather than as a co-author. I get that the point here isn't publishing, it's kernel development, but authorship is still quite important for a professional C.V.