Dr. Rush acknowledges that Young's tinkering ultimately has made no difference. The ship is hurtling into a star, and Young's actions haven't caused that. I think, in a way, Dr. Rush places the responsibility on his own shoulders; he just wasn't able to learn enough quickly enough to save the ship, the crew, or his own work.
As the ship draws toward star, closer and closer, there is aboard Destiny, a sense of fatalism, and even awe, about the sort of end they are all out to meet. Col. Young meets that end tearfully realizing he will never see Emily again; Sgt. Greer (Jamil Walker Smith) can think of nothing more wondrous than dying this way. Dr. Rush goes to his quarters to finish a "truly mediocre" book, a mass-market paperback (a sci-fi thriller, perhaps?), listening to a classical piece on his iPod. The melancholy, haunting violin solo, in retrospect (given what we learn about his wife in "Human"), perhaps brings him closer to his deceased wife Gloria. Is this the way they ended each day of their marriage--lying in bed, listening to a peaceful bit of classical music, reading side by side?
But as too much time passes, Rush wonders why they aren't dead yet. Rush is delighted to realize that they're all still alive, and that he'd been wrong. Had he an inkling about it--that Destiny refueled using the stars? Whether he'd had a theory or not, he is just flat out excited that they're not going to die.
Now that they are going to live to see another day, they must get the shuttle back aboard the ship. Everyone: Young, Rush, Eli, and the crew of the Shuttle now must work together. Requiring trust among all of them, each plays a role, finally working as a team, and really for the the first time. Once the shuttle is finally back aboard, the crew can celebrate a small victory.
The final scene of the episode still troubles me, even after many viewings. I understand why Rush doesn't want to celebrate with the heroes of the day. He brushes aside all mentions of his courage in removing his name from the lottery and his role in saving the shuttle.
In Rush's opinion, there is not all that much to celebrate; they are really right back where they started before the power went out, if only with more reserves aboard (which is a good thing). They still know little about how the ship operates, how to control it or where it's going. This is Rush's main focus, and besides understanding how Destiny is powered (no small thing, to be sure), there is still too much he doesn't know.