There was a reason I made clear to mention GPL advocates. There are differing definitions of "software freedom" that target the developers of software and the users of software.
When your political movement aims to ensure that the source code for the software that people are using is actually available and stays available then you need something like copyleft.
If your idea is instead to ensure that people are free to release source code for free if they wish, then there's not actually a battle to be had! That was how software started out after all, but that was also what led eventually to users being closed off from their source code.
RMS explains it better than I can: http://www.gnu.org/philosophy/open-source-misses-the-point.h...
(Unless I'm misunderstanding, you can charge for GPL software, you just cannot charge for the source once they've got a binary. You also can use your own fork of GPL on your hardware without releasing any source.)
See https://www.gnu.org/licenses/gpl-faq.html#DoesTheGPLAllowMon...
I believe this is no longer true (at least in general) as of GPL v3. In fact this "Tivoization" is one of the very things the GPLv3 was intended to combat.
Software-as-a-Service is another thing they were aiming at... I don't know offhand if it made it into GPLv3 or not.