
Can Loki project himself when he is sitting as Yggdrasil? That is my theory of his appearance here. He can send infinite such projects anywhere in the timeline.
The way I see it, Loki can project himself (one of his classic magical abilities) in any reality through timespace, through the yggdrasil. Then, he can time slip to that projection, while sitting in the throne.
That would be a cool power.