(as you know) The FSF require contributors to their projects to assign ownership of the works to them...

[email protected] Thu, 03 Jan 2019 05:28:09 +0000

Newsgroups	gmane.linux.kernel,gmane.linux.gentoo.user,gmane.linux.ubuntu.user,gmane.linux.debian.user,gmane.os.freebsd.chat,gmane.os.openbsd.misc,gmane.linux.debian.user
Message-ID	<[email protected]>

A license without an attached interest is revocable by the owner of the 
property.

The FSF require contributors to their projects to assign ownership of 
the works to them: For the FSF the license is not enough.

Put two and two together.