Racism is a motive, not an act.
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Determining the true motives behind a person’s actions is always difficult (arguably impossible). That’s why there is so often the lazy desire to bind a particular act or a particular group of people with a defined motive, regardless of the truth of any individual incident. Motive and intent are certainly important, especially in addressing future behaviour of an individual but consequence regardless of motive, is important too, especially in more disconnected or abstracted situations like this.
Focusing on the potential negative consequence of an act mean you don’t have to deal with the difficult task of proving a motive. Of course, that also applies to blindly accusing someone of racism regardless of what they actually say.