We don't know what sorts of facilities there are outside of that door. It's possible.

[And frustratingly likely. He actually frowns a bit, but it's probably difficult to tell given his eyes are still on the stars glittering above.]

I think... once people start getting closer to 63BP, it would be good to mention the possibility. Even if their idea was to leave the facility and get help for the rest of us, I doubt Zero would let them.