"Connecting this problem to conferences is an interesting way of saddling the organizers with a moral liability - a positive burden of action - for limiting the behaviors of attendees."
Well put! The burden of action you describe sounds like it dovetails well with the burden of action that comes from wanting people to come to the conference you organized in the first place.
"Having to conjure up some sort of quasi-judicial system can't be very appealing."
Again, well put! I'm sure there are people out there who enjoy telling people how not to be jerks in explicit detail, but I they think all have jobs as lawyers or politicians or FSF employees or something. How exactly does one say, succinctly and unambiguously, that taking photos underneath women's skirts is not okay without also banning merely annoying and unpleasant photography? It takes some work. I ended up with the phrase "harassing photography or recording" - not an elegant piece of writing by anyone's standards.
"Ostracism is a time-proven penalty that moderately aggrieved groups can perform all by themselves. Not good enough? (The police is there for the major stuff, of course.)"
Ostracism works pretty well when the people doing the ostracism are part of a powerful majority. However, I and at least 9 or 10 of my friends have been ignoring the guy who grabbed my ass at LSF for 2 or 3 years now but it unfortunately doesn't seem to have stopped ass-grabbing at open source conferences. I tried ostracizing the popular kids who were mean to me in middle school but that didn't seem to work either.