The air quotes around 'right' are interesting there. Yes, violence against Nazis and Fascists is acceptable. Do you disagree? I thought it was pretty much settled, we did a whole world war about it.
None of his views had anything to do with Naziism but failure to fall in line with all of the Left's current positions makes one "a Nazi" to them. And yes, much the same way as right-wing extremists like to paint all 'liberals' as "gun grabbing Marxists." The difference is you can find a lot more liberals who would happily glorify Marx than you can find Americans of any party who would glorify the Nazi regime or its acts.
In case it's unclear, I do not support Nazis either.
It's like a square and a rectangle. All Nazis are fascist, but not all fascists are Nazis. It's just like how I'm an environmentalist, but I'm not a member of the Green party. It may seem pedantic, but I find it's important to be exact these days because fascists love weaselly word games. Kirk was not a member of the National Socialist German Workers Party, but he shared the majority of their general beliefs and behaviors and those are undeniably fascist.