This is all according to his plan, he has never swayed from his goal of immortality and ultimate knowledge. Through his research he discovered all the secrets of the Shinju even being able to replicate the Juubi's genetic material to create mini Juubi minions capable of mangekyo sharingan as well as creating test tube grown Uchihas knew as "Shin" or in English "New". His obsession with sharingan drove him to this method, and he intends to dig even deeper than Kaguya and discover the true dark secrets of the Shinju, it's nature, and it's power. He now knows of a being even greater in strength than Kaguya and he seeks to take that power for himself. First he needs a living non relocated Uchiha vessel, his Uchiha clones are not capable of controlling the power he seeks, so he desires Sarada's body as he knows Sasuke can counter his ritual. He will take Sarada's body, revive the tree, eat the fruit, open a portal, revive Jashin, then become one with Jashin somehow.