<I disagree that Fields "wasn't acting as part of a side.">
His mother agrees with you.  It was her understanding that her son was going to a rally to support Trump; and so he did, by his lights. Did he go to Charlottesville intending to murder?  Or was he "inspired" by the company he kept when he got there? We don't know yet, but we probably will. 
 http://www.nbcnews.com/news/us-news/mother-charlottesville-suspect-says-she-thought-rally-was-about-trump-n792216