Sorry, but you make the pornographers argument for them. The issue is, is the harm in child porn to the child being exploited or to the adult viewer. Certainly we could make the argument that there is great harm to both.
Although I detest porn, as a conservative, I am adverse to the government regulating what I can watch in the privacy of my bedroom. Ergo, as an adult, let me be responsible for my own viewing, not the government.
This leaves the issue of harm to the child. If there is no human child involved, if it is simply computer driven animation, then there was no real human child to be injured.
I don't like it, but the court is right on this.
Pornography harms all. It denigrates the human race. Period. If you want to blather about your "right" to look at dirty pictures go right ahead just don't try to "justify" it with me or your Maker because it will fall on deaf ears.