Weren't the crew already doomed before WAU

[Mudbill]

That's why the Ark was made. Because no matter what, humanity was eventually going to wither down there, and so they wanted to create something that would last; the Ark. I'm sure they were working on the Ark shortly after the comet struck, knowing that they would be doomed. That's why they looked for any way of survival (if you can call it that), which made some people believe they would transfer into the Ark.