Look, I have worked as an expert witness in computer forensics and helped put Pedophiles in jail for having illegal pictures and has lead to prosecution for other larger crimes. I also have a 9 year old boy at home so no I do not consider this a joke.
The problem is that Sony cannot be expected to prevent these incidents from happening. The best Sony can do is cut off their accounts and maybe even contact law enforcement when something happens. However, that does not prevent it from happening.
This is my personal feeling and I respect what you are saying but I don't necessary agree with the level of enforcement you would like because I don't think it is possible. All online games pretty much say online content is not rated.
If my son wants to see tips for Knack then I have him look on Youtube because it is so heavily monitored that someone is normally not going to pull out their dick as you put it. I think parents have to be more vigilant in today's world. I am not saying it is unreasonable for you to expect Sony to keep anything hosted on their servers that really is pornography (not a crude drawing or 3d model) off their servers. However, I do not have my 9 year old play online games because the language is horrible from all the kids. Yes my kids has heard that language a lot but I don't want it reinforced. He is still just nine years old and I don't want him to think it is acceptable for him ever to use that type of language at this age.
I really think the only difference in our viewpoint is I don't think Sony can prevent the bad stuff from happening and I try to monitor and prevent as much as possible. You want your children to be able to play it the Sony world like it is Disney World. Unfortunately, sometimes there are people having sex at Disney world behind some trees that come into view with other people. I am sure Disney would arrest them or kick them out of the park but preventing them from seeing it in the first place is very hard to do.
I wish I had a better answer for you because I sense your frustration but I think that some of this stuff is unavoidable. If it happens, make sure your kids report it to you right away and find out the username and report it. You can even call law enforcement although I doubt you would have any luck going that route.
Good luck,
Dean