Jason Birch is right in wanting to use rel="alternate" in his KML atom:link, and the OGC KML spec is wrong in limiting us to "rel=related". Andrew Turner has written even more about what you can do with "alternate" links here. I remember commenting that the KML spec's public comment period was a bit short and ill-timed (Christmas 2007). Perhaps this error would have been caught otherwise?
Related: kml description considered harmful