Terrible as it is, I see his reasoning as well. The only alternative would be to prevent them ever leaving.
Plus Lou is working to know why there is zombie, its going to disturb him
And when they get people like blonde boy attacking them from left, right and centre out of the blue because they have no idea about the situation outside? A problem their former master most likely caused? It's not their fault, right? It's still people like Finn's fault, right? Y'know, that's what racists said. Ktbn.
I think that caleb is right. If they let every people who need home this will be sans fin