You want the author to mean something else than you do by the word "racism".

But the author's definition was the dominant definition for a good two decades at least. You can't just declare they're wrong and be done with it. You have to make a compelling case not only that your definition is acceptable, but that the other definition is so wrong as to be unusable.

Otherwise, just accept the different usage (maybe point out the distinction) and address the content.

(You did address the content too. I'm just pointing out that your objection to the terminology is inadequate to make a good argument.)