Originally Posted by Chance Jackson
Im pretty sure in Odin's Opening Narration he mentions the Aether could not be destroyed
No- during that narration Odin said that they believed the Aether was no more. It was Bor himself that said it could not
be destroyed during his private dialog with the Einherjar. The more I think about it even Odin did not know its true nature because knowing his impulsive son, he would've shot down Thor's plan right away.
I'm sure the reason Bor let antiquity think it was destroyed was so that no one would ever seek it out. Malekith used the destruction of Svartalfheim to cover his tracks. Bor did not know that Malekith was still alive.