I think it's pretty obvious that people who are visibly "not white" - whether Black, Asian or some other visible minority such as orthodox Jewish - will experience racism very differently from those who can easily "pass" as white. It would be ridiculous to try to argue otherwise, and I guess that's what Diane is trying to draw attention to.
That doesn't mean that other groups don't experience racism, though, or that it is any less traumatic and damaging when they do. We know that some of the most horrific racist atrocities in history have been perpetrated against people who "look white" - the massacre of six million Jews by the Nazis is an obvious example of this, and its impact continues to reverberate across the generations. Antisemitism and prejudice against other "white" minority groups is real, pervasive and persistent, and the impact on individuals can be profoundly damaging.
Aknowledging the specific daily challenges of those who do not "look white" does not mean that we need to minimise or dismiss the importance or the impact of racism for other groups. "Different" does not have to mean "less".
So I do understand what Diane is getting at here, and I think she has a right - perhaps even a duty - to make her point. However, I am very surprised after the previous incident that she has chosen to express these views again without having taken a bit more time to qualify what she is saying and to make it very clear that she is not minimising or dismissing the very real impact of racism on those groups who are less visibly "different".
There should be room for a more nuanced conversation about this, while acknowledging that racism can be horribly damaging for different people in different ways.