>>105375838They actually do have sex openly, and get told to knock it off by the police.
If the police crack down on simple nude violations, they'll overextend themselves and be unable to maintain order. Also, don't forget who has the political power in SF.
Realistically, keeping the parade goers from getting hopped up on poppers, and openly masturbating in the faces of 10 year olds is slightly more than the police can manage in SF.
Ironically enough, it's the older gay people that do more of the moral enforcing, especially when it's an out of control underage twink on the loose.