I really think that Tobirama will use this to make Hashirama kill one of his younger brothers. Then after this Madara will find out which will be his defection to the leaf's catalyst. I mean think about the poetic justice. When Madara was first revived remember how he called Edo-Tensei an abomination to the natural order of life in the world. Also we have been seeing Tobirama display his techniques more Ie. The flying thunder god slash.