The broad history of violent bigotry in the United States does not get magically forgotten by people just because they write code for a living. And that history and that present reality means that many things are not just abstract propositions but are direct threats.
> And that history and that present reality means that many things are not just abstract propositions but are direct threats.
Historical context alone does not make a direct threat. A direct threat is a direct threat, and right now being accused of racism (no matter the truth of it) is far more scary than racism itself.