When survival is at stake and weighted upon every decision, developing a healthy level of distrust with those outside your immediate family/group is important. For that matter, I would consider it even to be a very wise outlook to adopt even now in today's world. Thinking of things in such a way does not necessarily mean you have to be hostile to outsiders. One only needs to understand the truth of human nature: while some people will be genuinely goodhearted, the majority of them are out for themselves, so it's smart not to fully give yourself over until someone has proven they are worthy of such trust. The thing is that living like that (and now I'm referring directly to the full-blown societal collapse that the characters in the show have been living through), being in that mindset won't simply go away overnight, even if an individual suddenly finds himself in a place of relative safety. That healthy distrust simply will not fade away quickly. Or easily. And, truthfully, that's probably a good thing. It could save that person from finding themselves falsely deluded by a false exterior.
Something important to remember, however, is that it works both ways: instead of a weak place making you weaker, it is just as likely that stronger people can make a weak place more strong. Also, it's not terribly unlikely that those stronger people might actually take it over as well, which is a real future threat all of us need to be thinking about if we intend on building a community and allowing outsiders to join. Rick understands very clearly that his group, his family need the Alexandria Safe Zone. They need to make it work, just as Glenn pointed out, because they were out in the proverbial "wilds" for almost too long before finding it. And so, just like the people who took over the Terminus community and essentially terrorized the residents into psychotic cannibal behavior (though, with this group, the takeover wouldn't be nearly as predatory in nature), Rick is making the point that he would sooner seize control for themselves and assert his own rule rather than leave it and go back out on the road.
He told the lady running the place (a former Congresswoman from Ohio named Deanna Monroe) that the world was all about survival now, and he clearly meant what he was saying. He's going to do whatever he has to do to ensure the survival of his family, and there's something about that to be very proud of as I see it.
The Walking Dead: The Complete First Season [Blu-ray] --- [DVD]
The Walking Dead: The Complete Second Season [Blu-ray] --- [DVD]
The Walking Dead: The Complete Third Season [Blu-ray] --- [DVD]
The Walking Dead: The Complete Fourth Season [Blu-ray] --- [DVD]
My previous reviews for this series can be accessed by clicking the links below: