Michael Christopher Koji Fox, AKA Fernehalwes.
I don't think the Garleans are even aware of Hydelyn as an entity, and see it as just a planet. Is there any mention of them having this insight, other than possibly gaius and possessed nael?
The reason is that it sound like Garlemeld (or at least Garleans) have no cosmology, and are persuing the primal issue from a practical standpoint, rather than the bidding of spirits and crystals. That results in some extreme answers, but these are also answers Eorzea was considering, it was only in the efforts of our character The scions and cid's crew that provided an alternative.
Omega doesn't necessarily have to be stolen to bring ruination, the gcs can just as easily be tempted with a solution that would "fix" things permanently.