The content on all SE sites is licensed under the http://creativecommons.org/licenses/by-sa/3.0/ cc-wiki license. I wouldn't be worrying about a bait-and-switch.
It's just another content farm looking for unpaid labor.
Because it's an excellent resource, it could be monetized with a paywall. We can't predict the future but we can learn from the past.
They're already monetizing it with http://careers.stackoverflow.com/employer
They don't really have much competition but I think http://snipt.net/ is a good alternative in certain situations.