Ideally, shouldn't this be customized to the user, so that liberal users get conservative messages sent to spam and conservative users get liberal messages sent to spam?
I mean, yeah, I guess that would be possible, but is it a good idea? Echo chambers tend not to be productive, so if the choice is "get rid of stuff that most people think is bad" or "get rid of stuff that most people who agree with you think is bad" -- and if it takes much more work to do the latter -- I can't justify putting in that work. It's counter-productive, and all to satisfy peoples' desires to hear what they already think.