"Seems pretty clear . . ."
Eh? Not to me it doesn't. To me it looks far more like a site that simply had poorly implemented - or forgiving controls.
The idea that allowing "immediate re-submission of the ad with the age changed", if originally entered as under 18 somehow implies the site was in on the act flies is about as far as one can stretch a bow.
I frequently enter details wrong in submission boxes and then correct them - either because I am rushed or busy with something else or simply have fat fingers and don't catch it. This policy - of allowing someone to resubmit - is likely applied to all the fields, which is what I mean by the control mechanisms being 'forgiving' - i.e. forgiving of genuine mistakes.
If there is compelling evidence that the site "encourage[d] the trade" then they lose the protections.
Here is the deal:
Sites like this are given 'safe harbour' protections so long as they are neutral as to the content stored/published and take reasonable measures to prevent illicit content. What measures are reasonable depend on the type of service it provides, of course.
If illegal activity is conducted over your network or illegal content stored on your service, then, while the perpetrator is liable, the service provider is not.
The case here is to try and paint the service provider as complicit in these activities and thus liable. there is no question over whether the 'pimps' are liable, only whether the site is also to blame.
While what has happened is undoubtedly horrendous, this case is not about catching those really responsible, but about trying to pull the website in as well.
It's at these times - when heinous acts have been committed - that it is so very tempting to pull out all the stops and remove protections like this. PATRIOT act anyone? Australia's Metadata retention scheme? All the surveillance regimes in the UK and France?
While watering down (or removing) protections at times like this seems like such a good idea, those protections don't magically come back when it's a less severe case - they're gone for good.
At some point, we have to say that freedoms and rights and protections carry the risk of guilty people getting away with crimes and we have to accept that. The whole bloody justice system is geared that way for god's sake!! Innocent until (unless) proven guilty. The right to silence (at least in the US). Proof beyond reasonable doubt. Reasonable suspicion. Probably cause.
We know that these conventions and laws result in criminals walking free, or crimes being committed that could have been otherwise prevented.
It's tragic, but those conventions and rights and freedoms protect all of us; you don't get to say that only innocent people should have the right to these protections and the right to a 'fair trial' because those things are how we find out whether people are innocent.
That was a rant, sorry.