In order to distribute software for which you do not own the copyright, you need to have a license. If you do not agree to the license, then it doesn't even get to the stage we are talking about. You can't distribute it anywhere (under international copyright law). If you agree to distribute the source code in order to get a license, then you have agreed to do that. Is that not what is meant by a commercially negotiated contract? There is consideration on both sides (one party gets to use the software, the other party ensures that the source code is available to users of the software).
Either way, I think this wording is terrible and it worries me greatly. However, my layman's view seems to fall on the side of the GPL being OK. I would be grateful for explanations on what I may have misunderstood.