When the apocalypse happens, please, with all due respect, stay away from me. Just kidding. I see where you are coming from, but I am not sure if I agree with it or not.
Hey people are cool and everything, but we're talking about the survival of the species. It's like getting immunised, it doesn't really matter if an individual refuses as long as most people do not. The important part is "herd immunity". In the world of Brink, we are given to understand that most of humanity has died and that the remainder are sinking into barbarism, or similar. The only safe place that is known of (across the entire world) is the Arc. The only safe place to live with electricity, television, pc's, refrigeration, medical supplies, the medically trained, and so on and so forth is the Arc. The Arc is the last bastion of humanity.
In this situation it's lovely that the Guests are safe and warm when the majority of humanity is cold and dead. However, let's not think for a moment that the Guests arrived in fantastic hundred-person chariots drawn by pegasi and captained by angels. The Guests are the people that made it to the Arc. Some of them were chosen, some of them were lucky, some of them murdered their way onto the boats and planes. They don't deserve to live any more than the billions that died.
My point is that the Arc is (as far as we know, speculation abounds thanks to Ishmael and company) the safest place left on the planet. It is quite probably the largest surviving place of knowledge and technology on the planet. No information we've been given can lead us to believe that there is any other home left for humanity. It must be protected, or humanity as we know it will find it's ultimate demise.
So be nice, and sink. Or get tough, and survive.