What you're asking for is what I'm very obviously doing, here. Again: "shutting someone out" does not mean the talking stops. I am almost pathologically inclined to continue bickering with someone, for the sake of a potential audience.
This ding-dong's false equivalence is equally obvious. They've contradicted their contrary insistence within the same sentence as some of those insistences. Most recently they've blamed it on the laws where this study took place. Last I checked... Stanford is in California. American laws do not say diddly fuck about drawings of Bart Simpson's dick. There's public-facing sites where you could find one in a heartbeat. The FBI is not out a-hunting them. Their legal troubles will mostly come from the Walt Disney Corporation.
Not that any country's laws could possibly make child... sexual abuse... materials... somehow include computer renderings of fictional characters.
If we want a polite and civil discourse, everyone needs to make an effort.
Why is that the highest goal?
The creeping demand for "civility" above all else is a detriment to conversational honesty. That doesn't mean anything-goes. Screaming escalations and blatant trolling are not the same thing as identifying bullshit and saying 'that's bullshit.' Saying so is not polite or civil, but surely it's important. Rules saying otherwise have been a gift to bullshitters. Moderation never comes down hard and fast enough on their fallacies, abuse, and manipulation, compared to how mods pounce on direct call-outs. Even in language and tone that would scarcely raise eyebrows face-to-face. As if 'do you still beat your wife' is ambiguous, but 'hey, get bent' is inexcusable.
Long ago and far away, the point of reference was a cocktail party.
Most forums are not debate clubs, or kindergartens, or any other equivalent scenario where a quiet 'what are you fucking talking about' would get someone ejected. They're indoor-voice banter. Constructive, ideally, and sober enough to side with well-spoken rationale over ingroup posturing... but somewhere that 'here's why you're wrong, jackass' will be judged on 'why' more than on 'jackass.'
And sometimes the person you're talking to is obviously drunk or stupid or both, but you can keep calmly telling them how they're wrong about everything that comes out of their mouth. Debate is not what's happening. Civility won't help. But you can keep it reasonable, and frankly, that's better.