It's because there's no situation in which you (I hope) or I could conceivably be accused of being child pornographers. It will never affect us and the people it does affect are the worst of the worst and are identified as such by police.

I have mild conservative sympathies and get accused by idiots of being a "Nazi" depressingly frequently. It's screamingly obvious that the rush to clamp down on "hate speech" is in reality criminalising political dissent. Which is absolutely guaranteed to lead to more violence, not less.

The line is in the little thing only backwards people seem to use these days... the law. In the case of 8chan, the US law. It is within the US law to praise terrorists under the Freedom of Speech law (1st Amendment). If you want to change that fact, you can try to change the law. For example, I'm a Czech citizen and it is illegal for me to praise terrorism or nazism. Anyways, until such time that the law is changed, any calls for mass action against 8chan are little more than mob rule. Also, it doesn't help your case than almost all calls for extreme action like deplatforming come from a fringe minority of society (progressive far left activists) who are typically orange man bad, guns bad, free speech bad, low taxes bad, low regulation bad as it makes it hard to find compromises for such a group of people.

i think cracking down on imagery created from this violent act or other violent acts is a closer equivalence to child pornography. alternatively, you could compare bans on lolicon to the censorship you are advocating.