I think HN should just add another tab: Politics. That way the need for flagging goes down and everybody gets what they want. The main reason why you would want to keep politics off HN is because it turns would be friends, collaborators and people that respect each other into opposing factions (just like religion does). But in the end IRL that would come out anyway so better to have it up front. So I don't think it makes a difference in the long run.