I know on LiveJournal communities that contain adult content are encouraged to have a moderated membership (with members having an age statement in their bio or their birthday listed) and flocked entries for NC-17. And just like InsaneJournal according to that link, they request that you have some sort of statement in your bio. That's been around for years already in LiveJournal.
I have a fic journal. I post adult content. I have, in my bio, a statement that says I post adult content and that if you are 17 years old and younger to please step away. I will even check the age of people who friend that journal and not friend them back if they are underage. That is what LiveJournal required at the time and that is what I'm sticking to until they say otherwise.
The only time I've flocked a fic was not for adult content but because the original author of the source requested no fanfiction be written and distributed. So it wasn't advertised, just put on my fic journal and flocked. I would have never advertised it and then make people friend me.
I still won't.
If LiveJournal wants to take my journal down because it fails the Miller Test, that's the chance I take by posting on LiveJournal (or InsaneJournal or GreatestJournal or wherever). I still have other avenues open to me to post adult-content fic. Until they do, however, I'm not changing my policy in the current air of overparanoia that is flooding LiveJournal.