The return fire (if that is what happened) would have been a clear case of self-defense, and the defender would legitimately have avoided arrest or public identification.
If we still had anything close to a "Rule-of-Law", of course.
The original report of this story was so wrong that I cannot be certain of what actually happened. The updated reports have a number of odd discrepancies in them as well.
An "alt-right" furry? I have low confidence in that detail. Smells like propaganda.
ANTIFA cleaned up their brass and lawyered up immediately? Confidence is high on that detail. We give "our guys" exactly the same advice.
Multiple armed ANTIFA at the staging point? Maybe. I always assume that they have armed cadres in the back ranks of these events nowadays.
I would not confront "protestors" unless I was with a sizeable party of friends who are competent fighters and blocked from leaving the area. There is no upside potential.
There is case law where a belligerent was prosecuted for murder when claiming self defense. It fails self defense if you start a fight and then kill the victim who was defending himself from you. In other words, was the original shooter the belligerent, or was he defending himself from a mob who started attacking him? If the latter, then the shooter who shot him should not be let off as he would be the belligerent.