I recommend that you add a "Politics" category to your TownSquare Forum and then only allow the user to select the category of postings they want to view. If people wanted to view your TownSquare board but don't like all the political comments, then this would allow them to only see their preferred categories.
There could be an "ALL Categories" view available, but that should not be the default category that one sees upon clicking the TownSquare section.
If the above were implented, people preferring to view the Politics category should have very little to complain about regarding perceived imbalances of topics assuming that they are categorized properly. Also, if you (ie. PW) staff believe that a posting is not categorized properly you could either move it yourself or delete it because of improper categorization.