First of all, the mere existence of Twilight Princess disproves that the Sacred Realm exists outside of the spacetime that Hyrule is in. Because if it did, then there'd be no Ganon in the child line, but there is. Ganondorf's raid on Hyrule Castle was a surprise attack, they didn't know his motives and they didn't know what was happening. He went right for his target. And obviously as a seemingly loyal servant of the King the guards would not have stopped him until after they saw what he tried to do.
In the OoT ending, Link is clearly meeting Zelda before his raid took place. And he'd warn them.
In the OoT ending, Link is clearly meeting Zelda before his raid took place. And he'd warn them.