I have seen similar suggested rules during #blacklivesmatter protests. I did not pay them much attention, but now that you mention it, it does seem controlling to monitor poster’s content. That being said, I think some of rules such as these are put in place to control a hostile environment such as #blacklivesmatter protests. I think in some instances, it was to help protect the image of the protest as a whole. Much of what people see and hear about protests such as these comes from whatever the media chooses to post. So I think some of these rules are implemented to protect and clarify the overall message.