You make the question uninteresting by its assumptions. You pose a hypothetical situation - a white cop killing a black man - which might be interpreted as a case of systemic racism, depending on the context of the killing. But then you impose the axiom that the hypothetical world in which the situation takes place is not racist. So the situation could not have been a symptom of systemic racism, by your definition, and any query about whether it was racist has only one answer, which directly follows from your given axiom.
So I'm left confused at why you pose the question.