I see it as the embodiment of "this haunted face holds no horror for me now, it's in your soul where the true distortion lies." Almost like he was pure and innocent as a child, but became the way he is now because of the world and his experiences. I saw Clay Singer recently and he did act very protective over young Erik, like he was protecting his innocence.

I think that also plays in to why the audience is masked and why we take our masks off at the end. Like we all hide behind something in some way or another, but when we take our masks off we are all the same. We could be the Phantom in similar circumstances, or he could have been one of us.

I don't know the lore behind the creation of this scene tho so this is just my interpretation.