"These lines are here to convince people" is exactly what I'm worried about.  "You own your work, not your ideas" doesn't convince anyone of anything.  If you either agree with it, it's taken for granted, or if you don't agree with it, your reaction varies anywhere from hesitation to downright hostility.  It's much too confrontational -- it's a statement, not an argument, not even an explanation.  There are ways of conveying that same sentiment without alienating people whose opinions are more nuanced than "copyright" or "copyleft".  "You don't own your ideas" is overly reductionist, and as it stands, I don't agree with it.  Ownership, particularly over thoughts, is a highly complex topic, and there is an incredible diversity of personal philosophies on the subject.  *Many* of those ideas are compatible with the kind of passionate, open community creation space we're trying to build.  By saying simply "you don't own your ideas" we are limiting ourselves to a very small subset of those philosophies -- a subset that I personally don't even belong to.  Are we being open and inclusive of those who *think* differently than ourselves, or just those who *look* differently?

On an entirely unrelated note, if you aren't familiar with git, you don't know what "forking" means.  That's a big problem for something as fundamental as a values statement.

Revised suggestion:

> Work with anyone or everyone, but understand that no matter how carefully you pick your collaborators, eventually your team will inspire another.  You may help nurture this offshoot, but you may not control it: your ideas are your intellectual children, and you cannot dictate their future.

Bifurcated ideas are like children, and the relationship you should have with them is similar.  Nurture them, foster them, but ultimately trust in them to find their own destination.  They are their own "person".  I'm not 100% happy with it, but I think this wording does a better job of saying "there is no such thing as a 'stolen' idea" without saying "you cannot have a sense of ownership in an idea".