There is only so far I believe you can place blame on someone. While it is obvious that you can blame someone who commits a murder for that murder, there's an increasingly tenuous attempt to blame someone who told them they should commit a murder that I do not buy into. It seems to remove the agency of the murderer to try and cast the blame onto someone else.
Writing about a behavior and encouraging people to engage in said behavior are distinctly different sorts of speech acts. I don't know what you find 'increasingly tenuous' about the very detailed and specific exhortations identified here. Writing such is of course not the same as committing it, but I don't agree with your position tha it's free of any culpability. Again, it seems like you're more troubled by people exhorting such behaviors being thrown off the platform than by the impact upon those targeted by such statements.
I'd be happy to die on the same hill as the guy who wrote "First they came for the Socialists, and I did not speak out— Because I was not a Socialist."
Please explain to me the vital public interest at stake in protecting explicit calls for the abandonment of due process and participation in atrocities by law enforcement, and incitements to rape, murder, and other crimes with emphasis on particular ethnic groups as detailed in the mentioned letter (https://lawyerscommittee.org/wp-content/uploads/2018/05/Clar...).
I find it odd that the idea of terminating an automated publication service is considered a greater moral ill than the idea of committing the egregious human rights violations which would have a far greater impact on the liberty of the target populations. Perhaps we could establish a calculus of social ills? I'm really anxious to know how many rapes, enslavements, and murders it takes to outweigh the injustice of someone suffering an impediment to publication of content inciting such acts.