Board Thread:Naruto Discussions/@comment-24531362-20140904111518/@comment-24593592-20140909124636

Elveonora wrote: No, Hagoromo was first to mention Obito's name.

He just mentions Kakashi continuing to be Obito's friend. Which happened long before the battle with Kaguya. Kakashi had to tell him that Obito helped them. The Sage's later statements implies that he doesn't know that Obito is dead.