I like the idea of a site where the admin has assured that they will not interfere with you unless they have to.
If an admin chooses not to interfere, that does not absolve them from the responsibility of what happens on their site. If they had the power to remove it, and did not, they share in the blame for the consequences.
Are phone companies liable when criminals use their products to talk on the phone? Are the developers of encryption liable for ISIS encrypting their calls?
Call me when CNN and Fox News get sued for lying, and when Sony gets prosecuted for starting trivial lawsuits to stifle free speech.
First off, I'm talking about culpability, not liability. Conflating morality and legality (not to mention censorship and providing a platform) makes your entire post nonsensical.
And in the context of culpability, it's obvious that such a relationship only exists when the individual with the power to prevent bad action is aware of the action. So in this case, where Hotwheels is not only a participant in the relevant boards on 8chan but has expressed approval of what's happening, it's easy to hold him culpable (and probably liable as well, for what it's worth).
If an admin chooses not to interfere, that does not absolve them from the responsibility of what happens on their site. If they had the power to remove it, and did not, they share in the blame for the consequences.