This was exactly my thought on Charlottesville.  People are so anti Trump they deny the video evidence of antifa "protesters" physically assaulting with mace, pepper spray, clubs and punches.  These are the same people that rioted and destroyed property during prior protests. 

A better approach would be to schedule the counter protest on a different day: ridicule the small group of racists marching and respond with a march 100x, 1000x, or 10,000x the size, but scheduled to prevent the group versus group violence.