For some reason, I am being blamed for the "failed protest"

This just by taking pictures of their protest and creating a non-editorial collage of the event. I would suggest to the organizers of this event that, if they want it to be successful, they should make sure that they have better control of their message and be clearer in their objectives. If taking pictures of a protest causes its failure, then it wasn't much of a protest.

Here is an example of a more successful protest, in the same theme, that was held in East Lansing, Michigan on the same day.

Something else to think about. Some people make better friends than enemies.