Rhetorical demand for citation?
It's only rhetorical if empty rhetoric is all you have.
You say yourself Spencer does not deliver deliberately inflammatory rhetoric designed to rouse the rabble.
And you agree.
He is also a cowardly liar (in his famous 'getting punched' video, he is asked if he likes black people. He nonchalantly responds 'Sure, why not?' I don't believe it needs to be demonstrated that this is a bald-faced lie).
There's a lot to unpack here. But first, let's be clear:
Cowardice does not justify violence. Lying does not justify violence. Even the two things together do not justify violence.
Also, cowardice and lying are not the same as fascism, Nazism, or any other -ism that you have so far listed as justifying a violent response. This is either special pleading, or else horrific antisocial madness on your part.
Okay, now to unpack. "Cowardly liar"? Think about this. He could have answered the question in an inflammatory way, but he didn't. Instead he gave an answer that was much less aggravating. It may be a lie, but it's totally reasonable. People lie about their beliefs all the time, to avoid confrontation. In many situations, it's the polite thing to do. Discretion is the better part of valor, but to you it's an excuse to beat them up.
Punching someone because you think they're lying is the bully's art. Punching someone because you think they're lying is the wife-beater's art. Punching someone because you think they're lying is the torturer's art. That's where we're at, now: You say it's okay to punch Spencer for lying about what he really believes. Of course, if he told you the truth about what he believes, you'd say it was okay to punch him for that, too.
So it's not really about punching him for being a liar. It's about punching him for what he really believes. Or rather, it's about punching him for
what you imagine he really believes. Not only can you not give any real examples of incitement to violence, you can't even cite his actual beliefs. Punch him for lying about what he believes? That you can condone, even though you have no idea what those beliefs are.
His infamous 'Hail Victory' following President Trump's inauguration and tweets such as 'The [New England] Patriots even call their Blacks 'White' [referring to running back James White]' tend to create verbal or physical confrontations, even if unintentional, per the Wikipedia definition of fighting words. So yes, I think his publicly declared beliefs suffice to be fighting words.
More to unpack!
Again, to be clear: none of these are fascism.
If offensive jokes on Twitter are the bar for violence, there should be a lot more people in the ER with concussions from well-earned elbows to the head. There should be a lot of comedians, pundits, and incontinent corporate spokespeople walking around with richly-deserved broken noses and black eyes.
Finally, "tend to create verbal confrontations"? That's how low your bar is? If you'd said he deserved to be heckled for lying about his beliefs, or for his tasteless tweets, that would be one thing. But you're saying he deserves to be beaten. Not for actually inciting violence, not even for actually advocating a racially segregated fascist state (does he even do that? do you even know?) but for lying about his beliefs (you think) and for telling bad jokes on twitter.
At this point, you have done more to promote violence and undermine civil society than Richard Spencer.