I don't agree there. Non-violence is really only needed when a regime/situation is being imposed that is violent. Martin Luther King was in that corner I beleive. Fighting and agression was the 'others' way of acting. Non-violence in violent sitatuions is possibly the 'noblest' humans can aspire too...
The US is and was pretty democratic... Violent regimes have been imposed in the Soviet Union, China, North Korea, Nazi Germany, etc... Don't you think there have been MLK's and Gandhis there too? The Gulag was full of them.
Nonviolent resistance ultimately relies upon an appeal to the values of the aggressor. If the aggressor has certain values, then he will not be willing to press his violence beyond a certain limit, which may enable the resistor to win. However, if the aggressor lacks such values, nonviolent resistance is, imho, little more than an abdication of responsibility towards oneself and one's dependents.
Generally, this distinction is most apparent in warfare vs. crime. The vast majority of people are moral and reasonable; a minority are not. In war, you have a lot of normal, basically good people on each side psyched up by a bunch of Hitlers to believe that the other side is evil and that they have to kill them in order to defend themselves. In crime, you have a small minority of predators within a population that prey on others' weakness.
In war, if one side realizes that the purported enemy is just a human being like them and not an aggressor out to kill them, they will frequently realize that war is all a scam and that it's not worth killing and getting killed over wealth or vanity. For a more personal example, see the many examples of fraternization in WW1 trench warfare.
In crime, the aggressors are not human to begin with, otherwise they wouldn't prey on other people. And if they see the target to be weak, all the better for them for they will be able to rape and rob them without risking injury to themselves.
In war, the spiral of violence leads to futile loss of life on both sides. In crime, the lack of violence allows a minuscule proportion of the population to commit a disproportionate amount of aggression and be released to commit crimes again and again. If violence would be allowed to escalate in crime as it does in war, criminals would be weeded out immediately for the simple fact that they are such a small proportion of the population.