It is neither. Nonviolent communication is a tough act but it is strategic. Verbally throwing down and launching ad hominem assaults is not violent, but it is not nonviolent. Some analysts call it "not violent," a sort of junk category into which they toss behavior that does not advance a cause, a campaign, or a movement, but is not physically violent. Some call it verbal violence. Whatever we call it, that sort of behavior is not strategic. It tends to produce more oppressive violence and it tends to dry up public sympathy for those who use that sort of pugnacious language.
Nonviolent communication, wrote the late Marshall Rosenberg (2003), "guides us in reframing how we express ourselves and hear others. Instead of habitual, automatic reactions, our words become conscious responses based firmly on awareness of what we are perceiving, feeling, and wanting. We are led to express ourselves with honesty and clarity, while simultaneously paying others a respectful and empathic attention" (p. 3).
Some of you are naturally great at this. Some of us need daily, even hourly, reminders. I certainly struggle with it when I'm outraged by hurtful conduct. My outrage is proportional to the gap between the level of hurt and the innocence of the victim. That gap is widest and open longest when the response is assertive nonviolent communication. That sympathy gap can shut fast if actual violence is the response but will also narrow significantly if the response is some sort of snarling reaction instead of assertive nonviolent communication.
Do brutes deserve nonviolent communication? Probably not. Do you want to build your movement for justice, for freedom, for environmental protection, for peace? Then be careful not to start closing that gap. The quintessential gap-slam came when the US was attacked on 9.11.01 and pretty much the entire world expressed dismay and sympathy until 7 October when the empire struck back. Since then it's been all downhill to ISIS. On a smaller but quite important scale, we saw the sympathy gap narrow significantly after the Ferguson, Missouri policeman murdered Michael Brown and nonviolent protests gave way to riots. The sympathy gap took a big hit in the Eric Garner chokehold murder when two NYPD officers were in turn murdered by an African American fellow who used social media before the murders to establish his motive and intent as related to the uprising against police violence.
Direct violence is the fastest and most certain way to smash the sympathy, but even verbal violence--even just hate-filled facial expressions and angry chanting--will start to close that gap and that gap is always directly related to recruitment of both supporters and activists. Using anything but strategically sound nonviolent communication is like leaving power and influence on the table. Someone else will grab it. Don't let them.
Rosenberg, M. B. (2003). Nonviolent communication: A language of life (2nd ed.). Encinitas CA: PuddleDancer Press.