User blog comment:Miskos3/Fairy Tail Chapter 486: The Fourth Guest, Review/@comment-24277053-20160523141935/@comment-7418318-20160523142823

But if she manages to actually seal Acnologia, it'd be a convenient way to "store away" Acnologia for the moment.

Right now he can just fuck up any scenario at will, but if he's sealed away he can be kept on ice for as long as he's not needed in the story without anyone complaining about him just flying around without doing anything. And then once he's needed for the story, he can either break out of the seal by himself or be broken out by some outside force.

I don't think that'll actually happen, but it could be a good story-move if done right.