http://www.seattletimes.com/seattle-news/crime/uw-shooting/this article goes into more detail, saying that the shooter had been sucker punched and had his hat stolen by protesters (so peaceful), so it's most likely self-defense out of fear at this point
think about it
if you had a gun and you were hurt and (unwillingly or willingly we don't know) got into another scuffle with protesters who you're uncertain you'd be able to fight off, what would you do?
and this guy calling for togetherness after he was shot seems really fake to me because I know that if an alt-right guy were a violent protester who was protesting someone like Reza Aslan (IDK) and he was shot after he got into a scuffle with leftists he'd be a little more willing to call off the fighting too
that's an innately human thing to do; when you get your ass handed to you, you say, "okay okay OKAY enough with that, let's try and be friends"
it could be that this guy is serious and that the shooter is an starfish who deserves prison
in which case good on you, one distinct example of recent right-wing violence compared to the
dozens of examples of leftist violence
nobody's perfect