That was something that Sam had never thought of before. Bobby was always making good points though and, now that the idea was in his head, Sam couldn't unsee it. All of creation, set to destruction just because of one, tiny, seemingly insignificant worlds problems. Could the apocalypse spread outward or would everything get sucked in? Sam didn't know if the seals would work in an opposite manner, but if they were capable of dragging people through the cracks and out to this side, he wasn't going to rule out a reverse situation just yet. This was the sort of thing that Sam would have gone out of his way to sit down and talk about with Bobby over a beer. Something that they could and probably would have discussed for hours, as the importance of something like that was the kind of thing that Sam refused to ignore. But right now? He didn't have the time to pay the idea any attention. He had to get to Lilith. If he could stop her and the apocalypse, then that was something that they could dwell on at a later time.
Sam didn't think that his words would have worked on Bobby. But not too long after they came out of his mouth, the man tossed a key at him. Sam caught it with a hand and looked across at him warily. He was really going to let him go? Bigger picture. Bobby saw it. Sam bit down on his lip and breathed out a sigh of relief. No fights. Sam was, at least, grateful for that. "Thank you," Sam said, with a grateful nod. "I will. I promise, Bobby. Lilith'll be dead real soon." Sam hesitated a moment, almost as though he were uncertain that Bobby was actually going to let him go through with this. Then he turned on his heel and set toward the Rover. He'd switch up cars soon. Take routes and do things that Dean wouldn't expect. Whatever it took. And now that Bobby was on his side, Sam knew that it was all necessary.
Means to an end. And Sam was gonna find that end real soon.