Sad, just sad. This must be why more developed nations are starting to see population growth stagnate. If China wants to control its population, it needs to implement a one-hobby program, internet or sex. To play devils advocate, what were the two options as actually presented to the participants?
"If you had 20-hours of free time a week, would you rather spend that time on the internet, or use some of that time for sex, knowing that any remaining time is to be spent staring at a wall?" Unless you overdosed on Viagra, most people have far more free time a week then they could spend having sex.
I don't know about most people, but the time I spend on the internet is usually not time taken away from my interaction with other people. My internet time is usually time I already have to myself, so any sexual activety during this time wouldn't really count anyway.