I don't write in E-Prime, but I think it raises a valid point: you can often clarify and strengthen your English sentences by avoiding the verb "to be".
> [The authors of E-Prime] describe misuse of the verb to be as creating a "deity mode of speech", allowing "even the most ignorant to transform their opinions magically into god-like pronouncements on the nature of things".
And I think that's appropriate here.
We are forced to identify explain specific evidence of behavior that John has done that show that he's a racist.
Saying that, "John in frequently unkind to people different from him" or "John commonly uses racial slurs" goes beyond applying a label. This kind of approach to describing the ways people's actions hurt others requires more work. The pay off is that this kind of claim is also harder to credibly dismiss as "grievance culture."
Mind you even when trying to stay close to E-prime I still miss the mark all the time.