Regardless of how serious you think this issue is, these policies are necessary. Not as a punishment or a threat, but as a promise to attendees that the places we gather in are safe spaces for any and all who would like to attend.
There have been many ideas as to what kinds of efforts should take place in order to ensure that each conference does its best to squelch harassment, such as a sticker system akin to that used by MENSA and posters declaring spaces safe.
Is this enough? What kinds of measures would you like conference organizers to take in order to ensure your safety?