The young man at the end isn't just a character. He is the author! Read that last chapter again. The author made the bank robbery because he wrote it , he made the man rape his wife because he wrote it.
I was thinking the exact same as you but then I realised that Markus Zuzak had broken the fourth wall... It's actually pretty amazing if you get it
(view spoiler)[The man with the folder at the end is the author of the book.
He put himself into the story and is talking to Ed, a character of his own creation. So in a way, the author is Ed’s father (in a “father of science” or a “father of an invention” kind of way), because he’s the one who made him up.
The author didn't go and talk to the bank robber or the rapist husband in the story. Within the story, these people never meet. The author "convinced" and "talked" each and every one of the characters into doing everything they said or did, by imagining and writing them that way.
There really is no evil husband. He's a fictional character, so he can't be convinced of anything. He thinks, says, and does what the author makes him think, say, and do.
The author is changing the story at this point, by basically telling the reader: Hey, I made all this stuff up to show you that an ordinary person like Ed, or even you: the reader, can do good things and change the world around you!
If you still don't get it, look up "breaking the 4th wall". The idea is that on a stage, you see 3 walls of the room the characters are standing in. There isn't a 4th wall, or the audience wouldn't be able to see the play. But the 4th wall would be there for the characters, because they are just standing in a house or building. The characters don't see the audience. "Breaking the 4th wall" is when the characters become aware that they are fictional and/or are aware of the audience. It’s like they broke through the invisible “wall” between them and the audience.
Ed says, "I am the message." because the book is a message to the reader. Instead of an Ace, we got a book. If you are inspired to do the kinds of things that Ed did, then you are continuing the story. You create the sequel when you do good things like: befriend someone who’s lonely, cheer up a stranger, be there for a friend, & make your own life meaningful. You and I are the new protagonists, and we help write the rest of the story. (hide spoiler)]
I was thinking the exact same as you but then I realised that Markus Zuzak had broken the fourth wall... It's actually pretty amazing if you get it