The GNU General Public License (GPL), unlike Apache-style licensing, offers perhaps the best way to prevent a community from forking. It's therefore not surprising to see the Collaborative Software Initiative turning to the Affero GPL Version 3 to help foster and protect its budding TriSano community.
Eben Moglen, director of the Software Freedom Law Center and co-author of the AGPLv3, agrees:
By offering the code under the widely used AGPLv3 license, Collaborative Software Initiative gives the user community the assurance of knowing that the code can be modified, customized, and shared in a low-friction way to suit their very specific project requirements. AGPLv3 was written as a roadmap to foster the most open, transparent and collaborative open source and free software communities possible.
"Open" is in the eyes of the beholder--there is a longstanding debate between the GPL and BSD/Apache communities as to which is more open--but there's little debate that GPL offers a more robust way to provide incentives against forking a project. TriSano will be better for having all participants rowing in the same direction. AGPLv3 gives them this.
One question, though: why AGPLv3 instead of simply GPLv3? Is there an element of Web-based distribution here against which CSI is hoping to guard?