If you look look at my comments, I do say there can be verbal bullying. I'm not recommending that someone escalate a verbal altercation into a physical one. I'm saying that zero tolerance policies prevent people who are bullied from fighting back in a physical altercation.
On a side note, depending on the state and the specific circumstances, if a bully utters fighting words, one could be justified to get physical if there was an imminent threat to violence. Of course, law and school policy are different.