Lacking any better choice, the owner of the business or the department assigned to that. If I send a letter to the editor of a newspaper, stating that there is going to be a wild protest, does the paper have an obligation to publish it? In my opinion, these social networks are not the same as the public square. And even in the case of an actual public square, there are limitations to freedom of speech in the case of inciting a riot, for example.

Trump continually lied about the 2020 election on Twitter, even though he knew that night he had lost. He had told  the Proud Boys / Oath Keepers / etc. to stand back, but stand by,

On Dec. 19, 2020, after an hours-long meeting with outside advisers about seizing voting machines that a White House adviser described in real time as “unhinged,” Trump tweeted: “Big protest in D.C. on January 6th, Be there, will be wild!” This was the beginning of Trump's attempt to retain power at all costs.

I contend that any publisher or platform has a right to shut this behavior down. Likewise for racism, antisemitism, sexism, etc.