I'm not necessarily disagreeing with the general idea that you're espousing, but your example doesn't quite work very well.   Freenet has the downside of quite possibly actively turning someone who uses it into a criminal just by its use, whereas it is likely much harder to prosecute someone for performing a transaction using BTC.  By worrying about who uses BTC, or how welcoming the project is to various people (we should welcome everyone to use BTC for legal reasons regardless of their political views), you're putting the cart before the horse.  I'm more concerned about building the clubhouse than who's on the guest list.
As for whether or not someone is accepting bitcoins for access to porn sites: I haven't seen it yet.  If someone wanted to make such a transaction, they would have to advertise it.  It can't be too prolific if no one has really seen it yet.