I think you're missing the objective of the policy. It aims at taking away the fear from potential participants to be harassed. Encouraging people with insufficient social skills to come is not going to help that cause especially if pressure is put on the other participants to engage with their harassers or even see them as "valuable".
In all high-profile cases that surfaced in the past years, harassment almost never took place in a presentation or pan- el discussion, but during "social events" which ostensibly were meant to foster community building like you propose. So to mitigate the risk, social interaction should be mini- mized.
Well, I think if you look at conferences as a whole, the biggest cases have been in presentations. Here's a list of examples:
http://geekfeminism.wikia.com/wiki/Timeline_of_incidents
Of course these are just examples that are sexist. I'm positive there are way more examples out there.
In general, the social events are optional, but that doesn't mean we should allow them to be free-for-alls either. The anti-harassment policy should also involve social events. If you've had too much to drink, then you should be cut off. If you harass someone at a social event, even a non-sponsored one, you should also fall under this policy.
- Ryan