If a client cancels a request for proposal, then connects are returned.
"Out of curiosity, why doesn't Upwork simply auto-close contracts as soon as the job is awarded to someone? I've seen other platforms have something similar to this set up (maybe Elance did?). "
Sometimes clients leave their jobs open in case they want to hire other freelancers, which is why they are not auto-closed. And Elance did not close a job, unless a client did. For both sites though, there is a sell-by date (generous).