I think there is a (small) conceptual mismatch in that when writing for embedded targets yor mind is more focused in the hardware than in that there is no OS, so the normal view of "this is for Linux, this for Windows, this for DOS, this for Mac,..." is dimmed. Thus, you don't classify your project first as "OS: None" but as "Processor: ThisOne".
Even though, indeed, the most proper (if not the only) grandpa board of the actual ones is Operating Systems.
Al in all I think Martin did well in putting them where they are.