Facebook is fighting against the "huge target on its back" effect. The bigger of an audience you are, the more interest there is in posting abusive content, whether it's spam, trolling, or something else.
The result is usually that you end up digging a bigger and bigger moat around your submission and curation process, so that your service is not completely flooded with crap.
I think this is what you are seeing here, rather than censorship of this specific link or cause.
I once posted a URL to a forum site I was developing for a community to Facebook, and somehow it set off the spam detector. For the next several months, I would get regular notices that a comment I left on another group's discussion was marked as spam, and was not visible to anyone else. I was posting regular comments, without links, apolitical, not critical of anyone, just adding to the discussion.
The notices have since stopped, but I still rarely get any response to my comments, and anything I post to my profile's feed usually gets "ignored" completely, while in the past I'd get a pretty stable number of likes from friends (in the low double digits or high single digits.)
As someone who has moderated a decent size sub-reddit in the past, I understand that there's no malicious intent on Facebook's part in this. They are just so much bigger than this one individual that they simply cannot see me, the same way I cannot see a bacteria, and may not notice a tiny gnat.
The result is usually that you end up digging a bigger and bigger moat around your submission and curation process, so that your service is not completely flooded with crap.
I think this is what you are seeing here, rather than censorship of this specific link or cause.
I once posted a URL to a forum site I was developing for a community to Facebook, and somehow it set off the spam detector. For the next several months, I would get regular notices that a comment I left on another group's discussion was marked as spam, and was not visible to anyone else. I was posting regular comments, without links, apolitical, not critical of anyone, just adding to the discussion.
The notices have since stopped, but I still rarely get any response to my comments, and anything I post to my profile's feed usually gets "ignored" completely, while in the past I'd get a pretty stable number of likes from friends (in the low double digits or high single digits.)
As someone who has moderated a decent size sub-reddit in the past, I understand that there's no malicious intent on Facebook's part in this. They are just so much bigger than this one individual that they simply cannot see me, the same way I cannot see a bacteria, and may not notice a tiny gnat.