What is wrong with this...
... is that you are being suckered by the Police who are the ones conflating separate issues.
They want you to think that "oh, he had indecent images of children, so that justifies them misusing other laws and stretching them way beyond any legitimate bounds simply to give them a better chance of getting a conviction".
They are trying to create an association in people's minds between child porn and "extreme writings" such that they're allowed to act as the Thought Police and get laws banning anything they don't like, even when there is *NO* evidence of harm at all.
As for "freedom of speech is a good issue to right about, but only when it involves consenting adults", what about non-consenting adults? What about all those people who are killed, raped and so on in many books and films? They clearly don't consent, so should any such writings be made illegal...?