Although your OP has few flaws in it, but i agree on the part that Oro was after Rinnegan (if that's what you are saying), that guy deciphered Uchiha stone tablet, knew about everything there is to know about MS,EMS,Rinnegan, and also wanted Sasuke's body, and if he activate MS in Sasuke's body, then i see no reason why he can not kill Itachi, and once he gets his hand's on EMS there is no problem for him to get the Rinnegan since now he can read the stone tablet instead of hypothesizing on it.