I really don't understand why the victim would say that it is not possible to contact people before the transaction, because as a user of AirBNB I have talked to hosts before and exchanged details about who I am, including full name, location, age, etc. The hosts had enough information to look me up on FB, find and read my blog, my HN posts, and whatever else they felt like looking up about me on the internet.

It is completely possible to vet your guests before accepting them. Now granted I do agree that it would be very kind for AirBNB to compensate her for the damages she suffered, but I do not feel like AirBNB should be held responsible as if they caused this to happen, because they certainly didn't prevent her from looking up this rogue guest before accepting the transaction.