In Coraline (2009), the Beldam made the other world, and all the other characters in the other world. Almost all of the characters help the Beldam even if they don't want to. The only character that stopped working for her was the other Wybie. Why is it that all the other characters have to work for her, but the other Wybie. Even the other father didn't want to work for the bedlam, but the Beldam was making him do it. But Wybie went against her. So why can Wybie do this, but no one else can?
In a video posted by the theoriser he suggested that all the "dolls" the Beldam makes to lure Coraline into her world are made out of soul sand. Thats how she makes her creations come to life, but the more soul sand she uses to create something to more "human" it is. By this I mean it is capable of rationally thinking and understanding things like a regular human would. My guess is the Beldam used a lot of soul sand to make other Wybie and the other Dad, meaning they sympathised with Coraline and wanted to help her escape. This is why other Wybie continuously helps her and the other Dad gives her the garden eye before he dies and tells her, "I'm so sorry," before becoming part of the broken world.
Wybie spends the most time with Coraline and that time with her is away from the Beldam. When you see the other father, the Beldam is either controlling him directly via the gloves, or is just in the next room. In the piano scene he says "Am I playing the piano or is the piano playing me?" it is supposed to be funny but it foreshadows that he is not in control of himself when wearing the gloves and sets up the scene where he attacks her until he can free himself from them. The other residents are replaced by monsters when things become unfriendly, so they are no help.
Therefore Wybie is the only one who can help her because he is the only one with the freedom to do so.
The movie is made by a book - "Coraline" by Neil Gaiman. I think that explains everything.
There is no logical reason for Wybie, because the directors just wanted to put a little boy in the movie for more drama. There is no such character in the book. In the actual story, Coraline barely got any help and it was only from the cat. Which is reasonable, because the cat in the book has supernatural nature, it is some sort of otherworldly entity. He understand the nature of the Other World in full detail, including its history and the terrible truth behind its facade.
Answer: Wybie is not fully developed character, because he was not supposed to be in the story. That's why his behaviour does not fit to the whole picture.
My theory: he can’t. Remember when the other father said “Mother Making Me”? The other mother created the world, so she has control over everything and everyone in it, right?
So maybe the other mother was MAKING Wybie help Coraline. Why else would he just blow the sand off his hand?
And at the end the cat walked through the sign, referencing the beginning where he could teleport. Maybe Coraline never escaped.