Comedy Central and the South Park Studios are fine with what I am doing right now, which means using the South Park style for a non commercial project. I ask for voluntary donations, but don't charge anybody for anything connected to the SP-Studio. That's what most fans do and it's like free advertising for South Park. So they allow it.
But if I want to do more it's a completely different thing. I mentioned some of these things in the blog post. For example if I just want to publish a free app in the App Store or Google Play Store I am not allowed to use artworks which I don't have the full rights to use. Of course there is a chance Comedy Central will not notice or not care - but if they do I'm totally fu**ed. I don't have the money (and no legal costs insurance) for an international lawsuit with a big company and this could ruin my whole life. So I will never risk to do anything illegal with the SP-Studio, even if others do the same things. It's the same with merchandising. I recently talked to a programmer about the possibility to create 3D assets from the 2D SP-Studio images to print the figurines with a 3D printer. What an amazing idea! But I cannot even think about looking into this right now because I am not allowed to do it with South Park characters. Then there are other people who use my pictures without permission... They earn money with fake South Park merchandising or Nazis print stickers with racist propaganda. Right now I can do nothing about it because they say: It's just South Park fan art and not your own art! This has become very annoying for me. They tell me my opinion doesn't mean anything because it's just fan art. This hurts. And I get a lot of requests from fans who want to use the pictures for their own projects... I have to say no to most of them because of the copyrights for South Park. Though I draw everything I don't have the right to make decisions. Last but not least the next time I need money for updates I want to have more possibilities than asking for donations.
Those are just a couple of the copyright reasons why I'd prefer the drawings to be my own. Apart from the fact that it feels way better to work on something that's not just a copy of something others were drawing first.

I am not as attached to South Park anymore as I was 15 years ago.