Good question. I’m guessing the excuse comes down to Harry coexisting with Voldemort again. I mean… at first, he dreamed that he had the ability, so that’s not the same thing as actually having it. He only really had it back when he was in Godric’s Hollow in the same timeline as Voldemort.
But does that mean that he was once again a hoarcrux in that timeline? Eh, I think that might have become a concern if he had stayed there, but he left very quickly.
If I had written this story, I would have stayed well away from opening this can of worms, unless the point was to deal explicitly with the potential consequences.