But even then, if all participants are consenting adults, who could grope each other infromally anyway, who cares?
As for why doing the project again would have been a mistake, asking people for consent is not a cost-free thing, and many such events work far better with fewer participants for reasons both obvious and subtle.
The real mistake theferret made was posting about this on the internet. I was involved in a discussion about the OSBP on the xkcd forums when the post happened, and was amazed by the degree of misunderstanding and overreaction among people condemning it. That was the sort of reaction theferret should have seen coming, and kept the project an invite-by-referral thing rather than a public recruiting thing.
We use heuristics when we don't have the time to think more, which is almost all the time. So why don't we compile a big list of good quality heuristics that we can trust? (Insert eloquent analogy with mathematical theorems and proofs.) Here are some heuristics to kick things off:
Make important decisions in a quiet, featureless room. [1]
Apply deodorant before going to bed rather than any other time. [1]
Avoid counterfactuals and thought experiments in when talking to other people. [Because they don't happen in real life. Not in mine at least (anecdotal evidence). For example with the trolley, I would not push the fat man because I'd be frozen in horror. But what if you wouldn't be? But I would! And all too often the teller of a counterfactual abuses it by crafting it so that the other person has to give either an inconsistent or unsavory answer. (This proof is a stub. You can improve it by commenting.)]
If presented with a Monty Hall problem, switch. [1]
Sign up for cryonics. [There are so many. Which ones to link? Wait, didn't Eliezer promise us some cryonics articles here in LW?]
In chit-chat, ask questions and avoid assertions. [How to Win Friends and Influence People by Dale Carnegie]
When in doubt, think what your past and future selves would say. [1, also there was an LW article with the prince with multiple personality disorder chaining himself to his throne that I can't find. Also, I'm not sure if I should include this because it's almost Think More.]
I urge you to comment my heuristics and add your own. One heuristic per comment. Hopefully this takes off and turns into a series if wiki pages. Edit: We should concentrate on heuristics that save time, effort, and thought.