Someone promoting child porn by his word, according to me, shouldn't be sent to jail. That's the freedom of expression. Nothing that you SAY would be persued by the Law to be a reason to send you to jail. The acts that happen then are something else.
Then obviously you are unacquainted of laws. For example:
If someone is accused, but there is marginal or no direct evidence and the suspect denies, in most cases he is not prosecuted.
If someone is accused, and there is marginal or little/no direct evidence and the suspect confirms (withing fitting reason), he is sentenced.
If someone is accused, and he performs no legal defense (read:
proper defense, according to the rules set by the court (i.e., not filing a defense through an lawyer)), then in most cases he is found guilty (or better said, the accusing party is being granted the accusation, due to the accused not properly following the court rules).