Well I agree, your friend was treated badly.
But I think this shows some of the problem with this type of scenario. It was bad your friend was treated that way. And also it would be bad had some leader treated someone who thought differently as if they were a bigot for not accepting CRT.
I have to ask, in the end, what's the goal of these sessions, pedagogically?
People do of course respond to others from a whole host of experiences and thoughts and feelings. But that may or may not be along the lines of race. It almost certainly includes many things besides race. It by no means only includes white people, nor is it caused by "whiteness."
Most people don't name more minor feelings of this kind racism. In my job, I deal fairly regularly with some drug user populations. There are some of them who for various reasons really put my back up, although they have never caused me a problem. I have to be aware of my own response when I am helping them, and I hope I'm mainly successful. I also don't beat myself up about it because I understand that many of these responses, like in and out group thinking, or being wary of people who behave in a way that seems odd, are based in evolutionary survival strategies. Treating them like sins isn't useful, I can save that for things that actually involve my will being engaged.
The problem with people like DiAngelo is that they see racism as inherently attached to whiteness, which is just an updating of old fashioned race essentialism.