Does it? What if the old geezer had snatched Deidara away and gone himself inside the coffin, to arrange a nasty surprise for Kabuto the next time he intended to summon Deidara to keep enemies distracted? Unsummoning a summon is of course natural, but for the coffin to appear there is just plain strange if you ask me.
It seems to me like the ninja alliance is doing nothing but arranging meetings and drinking coffee. Madara and Kabuto have had time to fight, kidnap people and mystic eyes, scout, spy, and do all kinds of nasty things fitting for villains. The good guys, however, have succeeded at nothing but sending two of their heaviest tanks away, in vain to boot, and holding a long meeting. Madara will be disappointed once the fighting begins.