I suspect it is called Osyluth because of the demon/devil debate. They probably had to do the art for the card (along with name) before it was officially decided upon and thus chose Osyluth as a name that did not signify demon or devil. At least I hope this is the case because I hate the names that don't include "devil" or "demon" in it. The latter gives the creature so much more name recognition.
PS - Any WotC people who read this, it would be nice if you could clarify their names on one of your blogs - as in will you be using Bone Devil or Osyluth in the DMG. I suspect there is a strong following for the former.
PS - Any WotC people who read this, it would be nice if you could clarify their names on one of your blogs - as in will you be using Bone Devil or Osyluth in the DMG. I suspect there is a strong following for the former.