Couple of things wrong with that. First, we don't know if Hagoromo acutally showed them the fight, they certainly didn't show it in the Manga or Anime.
Second, Are you seriously saying that Sasuke copied Madara's Kyuubi Susanoo, after seeing it, IN A FLASHBACK? That's not how flashbacks work.
Third, We don't know anything about Indra and Ashura's fight, except that it was pointless. Why are you assuming that Indra must have used on particular technique in it, with no implications that he can even use that technique?
