Thanks for bringing this to our attention; I can't say I've really taken much notice of the room description.
The GH organisation controls
In disputes or contradictions, the details in the GH organisation's help centre holds sway over those here - simply because we look at it more and don't review stuff here such as descriptions as much.
The chat room is merely communicatory
We use the SE chat platform simply because the project was born here and GH doesn't have huge amounts in terms of communication features. It should not be considered under the terms of the licence we're using: anything in the chat room is governed by SE policy and legal.
To answer your question about the hypothetical beans story, if someone wants to contribute something they are most welcome to do so; it will be licensed as all our work is, under CC-BY 3.0. Thus, it does have a derivative of copyright on it.
I'll update the room description to remove any ambiguity soon.