I think they are using 'adult' as a stick to beat the Internet with. I think their real concern is the availability of information and news on the web and the potential exposure of the Chinese people to dissenting views. They make a great fuss about the polluting influence of western decadence (which sells well in the country) when in fact they are concerned about how they can hid bad news when their people have access to up-to-date information from around the world.
Totalitarian regimes throughout history have understood the absolute need to control what information reaches their people.
