In my opinion (feel free to ignore it), it makes sense to create a tag if you have already at least three examples of things that could be tagged by it. A tag is a way to group existing content, not an way to create it.
I thought anyone could create new wikitags? https://www.lesswrong.com/w/create
If someone does create this, it might be helpful to have separate tags for literal protests and meta discussion of protesting, like we have with meetups.