It wasn't suggested anywhere that the Secret has anything to do with Azeroth. On the other hand, we know that the 5 sigils are in some way related to a place called the Sepulcher. I don't think he even cares that much about Azeroth itself, he seems to treat it more as a source for weapons to use against the Covenants. See Anduin. He's probably still going for the same thing he was the first time around, and he didn't bother ripping open the sky over Azeroth back then.
I'm not entirely sure if he wasn't just talking about the sword and helm when he mentioned the secret, either.