On the surface Linden Labs plan to filter and contain sexual areas seems reasonable, and is clearly an effort to expand the normal uses of Second Life. The thing is having travelled Second Life I can tell you that sex still drives SL. Maybe in 10 years it will be a place of business but like the overall Internet the sexuality on it continues to grow along with other uses.
Second Life is not really dirty, its just sexual. Its probably mostly a kind of therapy or just entertainment. Most people doing hard core stuff have already made their land hard to find.
What I am concerned about is Linden Labs following Flickr's policy of making sexual ghettos. Firstly for free speech reasons, one you start tagging and censoring you start imposing American deeply prudish and close minded standards upon the world. European and East Asian concepts of what is sexual are very different than American, and central Asia tend to be far more conservative.
When Flickr did this it just helped to insure that Flickr never joined the first order of Web 2.0 products. Flickr's policy was very invasive. And what happened was given the choice of being dirty or nice most people who wanted to have their images views went dirty. If Linden Labs makes retailers and recreation choice if they are sexual or not, mostly clubs where there is now some flirting, most will select to be on the sexual side of the fence. Linden Labs could end up forcing people to be more perverted. This is precisely what I saw happen on Flickr, as the filters came in the side became dirtier and dirtier. People NEED to be marked as "unsafe" in Flickr if they want to get any traffic.