Realistically what would be the percentage of total potential contributors that you are barring from contributing? Nobody can't say for sure, but my guess it is probably a single digit number. Even if you fix that someone else will be offended from another thing. When you try to enforce cleansing the community it is more likely to lose existing contributors that put that jokes in. People should be told if their behaviour is not optional in order to improve, but don't go stir up pointless drama in which you have no personal involvement with.