Perhaps only 100 people survive. Maybe no one survives. Should they take that risk or rather stay were they are and hang on as long as possible. That is the big question. That's what they're fighting for.
Stay = Security
Leave = Resistance
You don't know what would happen in either case. It's the same in the real world: conservatives rather "stay" where they are (They don't want huge changes, they dislike change) while progressives try to get forward (They try new things). It's comparable to the resistance and the security.
True. Neither side is really right. But I just stick up for the side that seems to need to be stuck up for.
Another thing is that they apparently only agreed to these harsh conditions temporarily. But now its been going on for 20 years.