I do think the veracity of Ché’s claim is fairly high. No one who is sane just seeks out violence. However, in order to get the thing that they want—in this case, a revolutionary moment—violence may be the only means in which to achieve that goal; nonetheless, if it proves to be possible to reach the same end without putting people in danger then that will always be the route most preferred. Whether a movement is a violent one or not hinges mainly on the reactionary forces—those who are attempting to remain in power. Once they deem it necessary to use violence in order to suppress activism, a whole new can of worms has been opened.
Like an animal backed into a corner, the revolutionary coalition will be free to fire back—usually harder and with much more reckless abandon. As Goodwin would point out, this reversion to violence by the hegemonic group could also prove to be detrimental by the simple fact that the perceived injustice done upon the revolutionary forces will bolster more support from the masses. In this way, violence would serve not to repress the troublesome rebels, but actually to empower them and give them even more numbers.
Interestingly enough, the revolutionary leaders need the masses just as much—if not more— than the masses need them. Without the prospect of mobilization, or simply the means to stage any sort of effective demonstration, an entire movement can go up in flames. Having said that, it is imperative that once the masses are acquired, they be led stage by stage in order to ensure that the correct steps are being taken to give the group the best chance at a favorable result. This can be a slippery slope, as the responsibility (and power) that comes with leading such a large group can lead to bigheadedness and even an eventual tyrannical pursuit of authority. This is what Ché, Allende, and even Baader—any movement leader really—must contend with and learn to balance.