Them not being all one big happy family isn't the problem. The problem is the fact that aside from Rush, none of the supposed leadership (Young or Wray) seems to be able to figure out that they should focus on increasing the odds of their survival instead of wasting time and energy on petty squabbles that decreased their ability to survive in the long term.
But... why do you think there are these "squabbles" are happening in the first place? It's because they're all desperate to survive, but disagree on how to best accomplish that. What sane adult would hush up and do what their leader told them to even if they thought he was inept and liable to get them killed? The military are trained to, sure. But the civilians? Fuck that.