Let's say you got a kid on the cusp of getting some big offers, but he's in a difficult situation at home, so he moves in with an aunt or uncle. No court ordered guardianship, but that's where he lives. Eligible or you gonna make him sit out? A lot of situations like that.
What if a kid is on a team, they get banned, it's not really his fault, so he tries to transfer, but it's not a bona fide permanent move? I could see that happening here.
Then some places you drive an hour up the road and it's open enrollment.