I'm posting this link because this is probably my own biggest stumbling block: the tone argument. Because of my own history with bullies and the way we handled conflict in my family, angry people scare me. I am hugely conflict-avoidant. I love intellectual debate, but once emotion gets in, I want to check out.
Predictable as the sunrise, some white person somewhere in a discussion on race will say, "But you'd get progress on racism/more allies/more sympathy/whatever if only you didn't speak so angrily!" Surprise, being the object of racism makes people pissed off. Dealing with clueless white folks trying on their new brilliant argument that POC have only heard for the 5,675th time this week is annoying and tiring. And when you, the white person, demand that POC modulate their tone to you when they are talking about how racism makes them feel, you are asserting your privileged "right" to control the conversation about racism. And you are making it their responsibility to make sure you are comfortable. Think about that for a second.
You are asking people of color to cater to your wishes. In a discussion of racism. What is that if not white supremacist?
So the next time you feel like bringing up someone's angry tone, step back and chant, "It's not about me" for a while until the feeling passes. Maybe a long while.