Actually I was discussing this several days ago with my LS, I think that something, possibly ultima could be trapped in the meteor and released when it touches down. Even one of the concept arts, with behemoth, showed it in the background.

Darnus even confirmed after the most recent update that it was actually a sin cast up into the heavens to stay there. So Darnus could be manipulating their emperor into thinking its a good idea to use dalamud to wipe us out, but really he wants to free the one he serves, currently trapped inside.