User blog comment:Omega natsu2/Chapter 359: Fairies vs. Hell, Predictions./@comment-5426822-20131102154732/@comment-7418318-20131102181159

That Gran Doma argued for making a move against Tartarus (or started to, until he was interupted by... well... being killed) is a good indication that he believed they could beat them, which would support that theory.