Actually, Treena is the only thing that is keeping Earth livable in Deletrius. Fact is, Earth is kinda perma stuck, and no Treena in a place with no sun or even cosmic backround noise would spell for a certain blue planet unlivable rock status.
A simple metaphor for why Treena being dormant wouldn't bring Earth back. If someone fires a gun, melting the gun would take the bullet out of your heart. The no magic event screwing up Treena's teleport happened, and is not reversible by removing Treena.
