I agree that it makes sense we will likely be killed. However, the universe is pretty damn big, and WT has a transport shuttle prepped for departure. While it doesn't come up in any of the canon material, it's not entirely impossible one or more people from LV-426 got away and went into hiding, or appear as nuts telling stories about things in the dark over a beer at a half-forgotten outpost somewhere.
Especially if it becomes known WT might want to keep those stories quiet, survivors might be a bit paranoid.
Just some thoughts, but either way it will be exciting to see where this all leads!