Once again, I'll need specific examples of brigading before I'll accept that. As far as the admins of imgur go, it looks like they were making fun of them on their own subreddit. As far as users going to other subreddits and expressing their opinion, that is their right. It's the right of others to downvote them if they want to or for mods to enforce subreddit or site-wide rules.
Look, to be honest, I'm not sure why you're supporting out-right censorship. Even if Reddit wasn't built around the principle of free speech, this is a huge violation of the sovereignty of subreddits. In the past, subreddits have fought against each other with brigades and hate, but they never completely dissolved unless they were illegal. I've seen moderation coups and admin sponsored civil war, but unless it was illegal, the subreddit itself was bound to stay.