I might've misunderstood the "flag" somehow, I thought it was intended to mark content that people consider inappropriate, and not provide tangible feedback to the author.
What I had in mind was a system where negative votes offset positive ones. That way you can properly review stuff, a bit like in real life.
Also forgive my bluntness in the comment - I didn't mean this in a condescending way. What occured to me is that having a strong feeling about something that cannot be expressed is not the equivalent of censorship, but a technical limitation. Discussion on implementation of it is another story, this is where the whole grind of blockchain consensus is at.