Time for Despair
Seems mostly that he wants to cut out bigger businesses that seek to profit off of his series, more than restrict content. I'd imagine that it has a lot to do with the reasoning behind why he refuses an official anime adaptation, in that he doesn't want people to become familiar with his work through derivatives too far detached from the source.
... Especially if he's not going to be getting money from it.
This so much. Kinda like Touhou is for the people, not for the big businesses.