Why did Ben, of all people, have the sole right to choose to stay in the sideways world after Hurley invited him to join the group in the church?
As set forth in the previous post on Sawyer and Juliet, if the sideways afterlife actually came first, and the island world was merely a testing ground for lost souls to fix their moral, emotional or other issues, then many of the sideways choices make some sense.
In the sideways world, Ben is a meek high school teacher. He has no cloud. He has no chance of promotion. He is like his fellow teachers seemingly in the dead end job with little personal gratification. He is also a trapped caretaker for his ill father who lives with him. As a result of this caregiving, Ben has no social life. It depresses him. But here, he accepts his fate.
But if he the opportunity, he would be a different, more assertion - - - aggressive personality. He received that gift when his soul wound up on the island. The island allowed his deepest, darkest and repressed emotions to surface and take hold.
In the sideways world, any repressed bitterness for his lot in life to take care of his ill father was taken out by Island Ben created the grand purge which included killing his father. The death of his father would release him from his duty to him.
In the sideways world, any strong, inherit shyness, introverted or anti-social tendencies were turned inside-out by Island Ben becoming a strong, aggressive leader of the Others. The power made him believe in himself. He could manipulate and control people like a puppeteer. He would always get what he wanted - - - something he would never attempt in his real life.
So we have Island Ben being the exact opposite of after life Ben. So why didn't Ben, knowing his island past, go with Hurley into the church in order to move on? He said he still had "work" to do.
We believe that work was somehow making amends or a connection with Danielle and Alex.
But why would he want Danielle and Alex to remember Island Ben? Ben did not have a loving relationship with Danielle like Sawyer had with Juliet, to be rekindled in the after life. No, Ben was a ruthless kidnapper of Danielle's child. Ben sought to capture and kill Danielle. Ben's decisions eventually led to both Danielle's and Alex's deaths on the island. These are not happy memories for either Danielle or Alex. Once they realize what sideways Ben was to them on the island world, one would have to assume that Danielle and Alex would be repulsed by Ben.
So why would Ben stay in the sideways world? Is it because he could do no better?
Or does Ben get a "second" island proving ground with Danielle and Alex? This time to get it "right." (I don't think that would be a sequel that anyone would watch.)
If the island was a training ground for Ben to learn to be more assertive, more independent, more open to social settings like romance and dating, we get a hint of that in the sideways arc when after Desmond runs him over, he gets the sympathy and respect of both Alex and Danielle, including a dinner invitation. But his change in the sideways world cannot erase the bad things he did on the island. And this is why it is difficult to reconcile Ben's sideways end game to that of Juliet's with Sawyer. Juliet found her soul mate on the island. Ben tortured his alleged soul mate on the island.
Unless there is some magical love potion that is made of an egomaniac losing one's hubris like Ben's fall from power in the island realm, it is hard to imagine that awakening Danielle is going to cause Ben anything but more pain. And maybe that is the punishment that Ben has chosen upon himself. To live out his purgatory existence with the deep dark secret of his island torments in order not to be cast off into the darkness, or become a whisper trapped on the island.