If that doesn't work make the part you don't like illegal. Enshrine something like the "right to be forgotten" stuff into law and make them take down threads if the people they refer to don't want them up.
I know it's hard to word something like a "right to be forgotten" without making it to broad and a tool for abuse of chilling speech but it seems worth the effort if the consequences are this dire.
If you would stop derailing the conversation with unfeasible solutions.
If you want an example for such targeting though, Liz Fong-Jones has a thread on Kiwifarms because she's outspoken and worked at Google (and thus being seen as more influential / more of a threat). The thread has also significantly slowed down after she left Google.
Read: to put a target on the back of anyone making an abuse report about the website.
If not Cloudflare, then someone else, that's the reality of it. We do not live in a world of no harm and never will we. All we can do is manage it.
When has this ever been a valid excuse for bad behavior?
Cloudflare loves to call back on the law when defending Kiwifarms, but then equate themselves to a public utility.
If the law intended for it, DDoS protection would be a public utility or at least a protected class of service that can't refuse customers. And if you say that it should be and the law is just lagging behind (and I'd tend to agree with you), I can say the same thing about the technical legality of a website that enabled and (indirectly) incentives doxing, harassment or even swatting (except on Kiwifarms, people might technically have a case for defamation, but good luck getting that prosecuted).
Why not? That particular service seems a lot like a volunteer fire brigade.
I'm sure their LGBTQ+ employees will appreciate that when they get doxxed, swatted, and harassed every hour of the day and night because they're providing critical resources to the groups doing so.
Their position probably really does come from genuine belief in principles of anti-censorship and free speech, but the version that LGBTQ+ people are gonna hear from them is that every death threat, every picture of them taken without their knowledge, every coordinated campaign of harassment, every SWAT officer pointing a gun at their face when they wake up, every suicide after years of abuse, has the full backing and support of a multi-billion dollar corporation, and there's nothing they can do about it. And they're kinda right.