I've been in the EA movement for a long time and I can attest Rationality did not play any part in the EA movement in the early days.

This is clearly wrong. You can watch talks or read about the history of the EA community by Toby or Will, and they will be clear that the Rationality community was a core part of the founding of the EA community. 

There are parts of the EA community (especially in the UK) that interfaced less, but there was always very substantial entanglement.

I think it's a minor issue that is unlikely to drive anyway who actually has a "hair-on-fire" problem of the type that a prediction market might solve. I am confident anyone with experience building internet platforms like this would consider this a very irrelevant thing to worry about at the business stage where Manifold is at.

I disagree with this. I think the obvious source of money for a prediction platform like Manifold is from people who want to get accurate information about a question, who then fund subsidies which Manifold gets a cut off. That's ultimately where the value proposition of the platform comes from, and so where it makes sense to extract the money.

I briefly googled it and it seems at least somewhat common: https://www.quora.com/Why-do-many-Australian-men-like-to-use-faggot

Also, I guess Australian's call cigarettes "fags" which I think guess is some evidence of the word being used more casually.

Not confident of this though, I've never been to Australia.

Some ways to use a slur in a non-real way: 

• You use it in quotes to refer to how other people use it (as we've been doing in this discussion). 
• You use it in a clearly light-hearted ironic way (this is dicier, but clearly sometimes possible. For example, if the slur is directed at a clearly non-applicable inanimate object in an ironic way, like, if someone were to list profanities in an exaggerated and joking way against a chair they just stubbed their toe against.)
• You use it in a very non-central way (like, someone talks about the historical use of the word faggot, or like, somehow uses it for it's other meaning "a bundle of sticks or twigs bound together as fuel.") 
• You have a substantially different cultural background (like, among Australians, friendly insults appear much more common, and calling each other "cunt" or "fag" seems not too rare)

There are probably some more ways I can think of, but these four seem like reasonably common causes of people using slurs with it being "real". 

I think these are fine hypotheses about the tradeoffs here, though I disagree with most of the analysis. I have thought and read a lot about it, since like, my primary job is indeed to handle these exact tradeoffs and to build successful platforms here, but this current thread doesn't seem like the right context to dig into them.

As one point, I think Manifold's basic business model is "take a cut of the trading profits/volume/revenue". The best alternative business model is "have people pay for finding out information via subsidies for markets".

I don't think Manifolds business model relies on advertisers or foundations. I think it scales pretty well with accuracy and usefulness of markets.

I'm choosing to interpret this as you wondering if I used that collection of words as a representation of the kind of soft opens some of the attendees engaged in instead of real examples (as opposed to suggesting that I was lying), but "fag", "retarded", "based", and "cuck" were all used quite a bit.

Yep, that's how I interpreted it, especially given that the other two seemed to me quite different (again, "based" really has no connotation with a slur to me and is just like a weird word that people on the Internet use, if anything it's a compliment).

Eh, I've been living in the U.S. for a full decade, so I think the "foreigner excuse" doesn't really work here, I think I was mostly just wrong in a kind of boring way. 

My guess is I just happened to have not heard this specific term used very much where I could see people's social reaction to it, which I guess is a weird attribute of slurs. Reading more about it in other contexts definitely made me convinced it qualifies as a slur (but also, relatedly, would honestly be quite surprised if people used it in any kind of real way during Manifest).

I think most broad platforms that get started do not ban "controversial" users from it. 

Allowing "controversial" subreddits did not cause Reddit to fail. Allowing "controversial" videos did not cause Youtube to fail. Allowing "controversial" people on Facebook did not cause Facebook to fail. Allowing "controversial" tweets did not cause Twitter to fail. Indeed, I think banning people instead of being an open or neutral platform is very heavily correlated with failing as a piece of online infrastructure.

I mean, I would really love to discuss this stuff with you, but I think I can't. Maybe in a year or so we can have a call and discuss bankruptcy law.