So I have this headcanon-
Based off his dialogue "Those foolish Bishops thought they could keep you from me in death. But instead they sent you straight to me." in the start of the game, and since there's no other lambs for him to use thus making OUR Lamb the last of their kind; the Bishops were doing something to prevent any lambs from going to him in death, perhaps consuming their souls (in the same way they consume follower's souls when transforming into their Eldritch forms)
Which means our Lamb's arrival was either an accident or intentional, and since Shamura already has shown to have a soft spot for Narinder, including sending him Aym and Baal so he's not lonley, and also the state of their mind at the time...I don't think it's too unlilkey that maybe it's Shamura's fault the Lamb was sent to The One Who Waits.