That's why I stated it is a semantic discussion.
On the one hand, I think this redefining is good. Because when we talk about the problems of racism and sexism, the prevalent form of negative discrimination (so in the west, racism by white people, and sexism by males) are what we tend to mean.
On the other hand, other forms of discrimination also happen, and we need words to describe them. Racism and sexism used to describe that, but by now such describing tends to feel bad. It tends to feel like drawing an equivalence between e.g. a white person not being able to use the N-word being 'just as bad' as the oppression faced by black people in America.
I feel we need separate words for both the systemic (non intentional) oppression of people by sex and gender. And discrimination based on sex and gender in general. Originally racism and sexism used to describe the latter. Slowly we are moving towards having it mean the former, without having new words for the latter. Ideally wish we had just come up with new words for the latter. But that would have lost some of the power that comes from calling someone a racist or a sexist.
In conclusion, semantics matter, and are hard.
If that is what comes to mind when people talk about white discrimination, then there is a large disconnect in the discussion when talking about the semantic meaning of sexism and racism.
If two people apply to a university and the critical distinction why one got excluded is race, then that is a negative discrimination. If two people are accused of identifical crime and the the critical distinction why one got a harsher sentence is race, then that is negative discrimination. If two people are illegally demonstrating on the street and one get violently assaulted for doing so, and the critical distinction is race, then that is negative discrimination.
Some of that negative discrimination harms white people, some black people, some both in different circumstances, and there is many more situation where such discrimination occurs. Same in regard to gender.