Besides that, up till now, the crew, including Young and Wray have treated him like a pariah; why would he socialize with them now? Rush also seems far too reserved, isolated, and guarded to be sociable with people he doesn't really know. But the crew, and especially Young, are trying to reach out to him, if only for the moment. So, Rush is being a bit of a jerk here.
But what I really don't get is Young's assumption about Rush; that somehow he'd known the ship would use the star to refuel and that he'd kept it a deep dark secret for some hidden agenda. So what if he'd known or suspected the truth? What possible good would it have done to let anyone in on it? He couldn't have known with absolute certainty, and had he claimed to have known, and kept the crew all on board, he certainly would have taken the blame for losing all their lives if he'd been proven wrong.
Rush neither affirms or denies whether he'd known. As Eli (David Blue) says, Rush's pure joy in realizing they had survived the star is proof enough that he couldn't have known for certain. But that tiny bit of doubt is enough to turn Young back into full distrust mode.
"Light" is one of my favorite episodes of season one. It has a great plot and some wonderful performances, as well as being beautifully shot, especially as the interior of the ship becomes bathed in the star's orange glow. The metaphor of the crew (and the ship) coming out of "Darkness" and into the "Light" carries through from the titles of the two episodes to the ultimate coming together as a team, and the unfolding of several main characters as they are revealed to us.
My series of pieces on Stargate Universe continues next week with "Water."