If Adar is one of the M-named Sons of Feanor that survived that would certainly be a twist. And it might even explain why he reacted to such hostility to the name of Sauron: Sauron was a willing servant of Morgoth, whereas the orcs are merely Morgoth's "creation" .
But in any case I came here to say that this plot line where if the elves do not get mithril they will wither away in less than a year is just every kind of stupid. Like, the shows origin of mithril is interesting, if unnecessary. But this whole, "Wow, good thing we found this this year or we would all be toast," is just bloody insane.