Why would Oro kill the guy that stayed with him through most, if not all of his trials and tribulations? The guy that cared for him when he couldn't use his arms? The guy who saved Anko so that he could come back? And yes Kabuto most likely did know that Oro was still alive in Anko and he probably wanted Sasuke's body so that he could feed it to Oro. Point is Kabuto is his butt-buddy and he's not gonna give up free ass lol
