User blog comment:SpookyBoogie27/Light Novel Spoilers/@comment-66.185.206.31-20130919191326/@comment-1359322-20130927071352

That was one of the joke topics on the chat where we called Mil-tan "the true strongest being in the DxD Universe". So X was saying if Mil-tan joins the Devils, the other faction would reconsider before attacking the Three Factions.