I suppose "Masada shall not fall again" means "always be stronger in arms than the people you are fighting". Masada fell because they were up against an enemy which was very much stronger. Nothing to do with any notions of non-violent resistance or whatever.

If you aren't in a situation to be stronger in arms than your opponents - if for example you're a republican in Northern Ireland, or a Palestinian in the Holy Land today - the only way you can be stronger is if you can outlast them, and take more punishment than they can give.

This means that, even if it's a struggle involving extreme violence, at its heart is a non-violent strategy. The violence is essentially symbolic - by which I don't mean that it is not lethal, but rather that its central purpose is not to achieve military victory, but to act as proof of a continuing resolve, and to bring it home to the people on the other side that they can never win. The purpose of non-violence would be to do the same thing, but in a way that did not poison the future in the same way, even if it involved as much human cost in the short run.