I thought it would be an opt in for the poster, something like:

• Users can create a private tag that opts out of appearing on trending.
• In exchange posts in that private tag can not be down-voted.

The only way to censor content in a private tag would be if all witnesses decide to not write content from a certain private tag to the block-chain. So you would need 95% of the community to think the content is obscene rather than one person with an agenda before the content is banned.

Expanding on the idea: you could allow people to register, own, moderate, and collect the curation rewards from their owned private tags.

Without a hard-fork to implement private sub-reddit style tags, I suppose an option to not to have your content show on trending, and hope agenda driven down-voters don't bother you would be nice.