@3rik #FreeSoftware can still contribute and build upon it. They just cannot be part of a corporation. Its similar to MIT and GPL. What is more free, writing code so some billionaire can make more money and you get health insurance, or working together to make your collective peers' live more fruitful? Both make open source code.
@dean As said, I totally understand the idealistic rational behind it (keeping code for the good cause), but in order to be GPL compliant a non-GPL license must permit to release any such combinations of code under the same GNU GPL license that the GPL code is using. This is e.g. the case for the mentioned MIT license but not for any "non-commercial but..." license except there is a specific exception in said Coopyleft license that allows re-publishing under GPL and I am not aware of?