Not that I'm particularly concerned about the petition, but it would be a little naive to think that a.) parents could maintain any real control of the internet and what their kids are able to do with it, or that b.) denying a child access to the internet is any sort of real option, or that c.) a parent would "supervise" their child for the entirety of the use of the internet.
Yes, there is only so much that can be done. But simple monitoring without any other techniques wouldn't help either, because the kids don't know the reason.
After all, if you make sex evil, you make evil sexy.
In addition to monitoring, I would be letting my kids know that the reason isn't because sex is evil and they shouldn't even know it exists until they're 50 years old, but because it can be tricky to discern what's virus-prone and what isn't.
Once they know how computers and the internet work (which I will be teaching them from a young age), the leash will more or less be off because they'll know the techniques for avoiding viruses, scams, etc, but they'll also have their own computer by then, which won't get replaced if they break it.