What entitles you to that level of control over email? If any of the emails you sent were modified by Google, you would be outraged, but we should just accept "editorial control" over Twitter, Facebook, HN, etc.?
I think that's the real debate happening here. It's not just about censorship, it's about exercising control over the content. Many feel strongly that this sort of control should be in the hands of the creators of that content, not editors/moderators/site owners/etc.
> This site also allows us to edit our comments, without the explicit consent of every person who responds to them.
I would be ok if the person who originally submitted the article made that change himself and there was a history associated with the submission that showed the change. That's the creator exercising control.
> This isn't a direct democracy, it's a news aggregator.
It's kind of acting like a newspaper though? If content is being edited, that's the job of an editor. I don't think it's such a far stretch to imagine top comments being edited to improve the conversation, etc. at that point, what's the distinction with a newspaper?