Its seems that, based on the positive media reaction to this, AirBnB has done everything right from the start:
Everyone is piling on them for screwing up the initial reaction to EJ, by not going far enough in offering to help her. But AirBnB didn't do much to help Troy (from the TechCrunch post) 2 months ago, and that story didn't blow up in to a PR disaster. They simply gave him a few free nights and he was happy.
So, it is impossible to tell if any given customer support issue is a potential "PR-nightmare". If AirBnB had over-reacted and offered Troy thousands of dollars (as was being suggested for EJ), they would have lost out - because Troy was happy with just a few free nights in AirBnB credit. How were they supposed to know that EJ (1) wouldn't be happy with what Troy received (2) Would make a scathing blog post and (3) That blog post would go viral. They couldn't have.
So, if you are a wagering person, it seems like the best course of action is to do exactly what AirBnB did: offering minimal support and grow until something really bad happens. Then come out swinging with a big apology and a big offer of support and restitution.
Since it seems like the media and public are willing to forgive AirBnB (judging by the reaction to today's announcement), this course seems like it may have been optimal compared to over-helping people like Troy.
Put another way: PR distasters are recoverable if you say you are sorry and ask forgiveness. Being too careful upfront and limiting your growth curve is not forgivable.