Reasons???
1.He can see everything from past to future
2.He has a great vision of everything is going on
3.He is the one who can give you revelations.
4.He observing all living things
5.He has connection with Konoha,Orochimaru was the one who knows the way to Mount Myōboku through Konohagakure because he was student of Hiruzen.
6.Sasuke is heading to Konoha,it must be Mount Myōboku