Before I begin, I have to say I think codes of conduct are a good thing, an essential element of a well run conference. In fact, I’d go as far to say not having a code of conduct is to neglect your duties as a conference organiser.
I know a few people who have organised conferences, some better than others, and none of them want a code of conduct. This is why codes of conduct often include some variation of “we don’t want to write this, we have to”.