...or they can have the option to "unsubscribe"
  from the actions of moderators they disagree with

This is a really interesting idea. Another would be to make moderation opt-in, e.g. you select the curated filters you want to apply to forum X based on their reputation for fairness and pleasantness. These might in fact be the personal filter settings of upstanding members, or a vote between a few such members.

Anyway, thanks for the yummy food for thought.