I'm pretty sure Stephen King was sexually abused as a child, and I'm pretty sure this scene in It is just another example of him trying to work through it with his writing. It's a recurring theme in a lot of his work, and some of it feels like he's speaking from direct experience. The Library Policeman specifically. He also mentions in On Writing that he has sparse memories of his childhood with long blanks spots, which is pretty standard for traumatized kids.