"Well, he does have more of a presence in Mementos than most of us do, but that shouldn't be the first resort, or even necessarily the last one. The first step is making sure the relevant information can stay in his head long enough for him to understand his position, which will require a more delicate touch than trying to impact his Shadow. After that... we can't make him do anything."

Sparrow's Shadow is itself a very compelling reason not to start with Sparrow's Shadow, but also: Haru has a chance to not be her father about this, and she's taking it.