Invocation of Whataboutism is an easy cop-out to never have to look one's self in the mirror. It's used by people in glass houses who only want to throw stones at their neighbors.
It's also not applicable here since the grandparent already did a relative comparison of China with the supposedly better "western track record", so this comparison warrants a response.
No, the argument is more like saying that Germans calling the allies as beasts for what happened to Dresden should also look at what happened to the Jews.
The difference, in case you didn't notice, is that while racists are indeed racist and people against racism aren't, here the two sides are equally bad.
It's also not applicable here since the grandparent already did a relative comparison of China with the supposedly better "western track record", so this comparison warrants a response.