generally speaking, if the group is autonomous and they all agree to have rules and enforcement, i say let em have at it. they are not anarchists. if they try to impose their rules beyond their group, they will be met with the force of all who oppose them. like this anarchist and my well-armed voluntary associates.
but perhaps more to the point, if some people decide to impose their will on others, and those others are incapable or unwilling to prevent that - even with all their trusted comrades - then i guess they are fucked. kind of like... most of modern human history. nobody i know, anarchist or otherwise, has any silver bullet for changing people's minds and behaviors. (lead bullets, maybe, heh heh).
one thought is that in a different world (community, whatever) - one where there were no hierarchical institutions etc - people would think and act differently than they do in this democrapitalistic shithole that is so ingrained it is taken for granted by almost everyone. and the need/desire to impose on others would not be the status quo. folks could actually relate directly with those they choose to, and conflict would likely be handled quite differently.
that's just one thought.