Child pornography is a bit of a different story. Its flat out illegal no matter who has it or where its displayed.
Riots though!
If I were to write a book (shoot a film or whatever) on how to start a riot there is nothing illegal about it. If I were to write a book saying we are going to riot on this day at this time and this is how we are going to do it... Then yes I am guilty of incitement. For it to be applicable to Assange he would have to get on Wikileaks (or I suppose anywhere really) and say "We are going to hack <government or corporate entity> next Wednesday by way of DoS."
Let me read up on this Espionage Act. BBL.