Gabriel is only partially right. He said that they wouldn't help people before themselves. That is complete bulltrout. Glenn tried to save that guy, Big Red saved Franceen, and several times before this episode they tried to help people who weren't apart of their group. I think in the end Rick does have some evil intentions and does want to take the place over completely because he does feel they are incompetent, but they are.

Some how they have managed to make it work without them though but I don't think the zombies are their biggest threat. It seems pretty clear that other humans have always been the biggest threat in this show.

Also Michonne and Carl saved Gabriel's ass. How quick he forgets. He is selfish just like those people and would rather save his own ass than someone else's. I'm not sure I get Maggie's reaction either. Maybe she feels some what guilty about what happened in the church? Though she shouldn't because it was self defense. Those people were disgusting.

I also think it's wrong to lump them in one thing. Though they are Rick's group, they are all individuals. While Glenn, Michonne, and Abraham (Big Red) may be good-hearted I don't think Rick is anymore and I think he sees every opportunity now as a "what I can get from them" opportunity.