It is that the belief that the police may interact with the situation in a racist way isn't an inaccurate one.
Ultimately systematic racism assumes white superiority not just institutionally but also individually.
Someone like AC might not believe herself to be racist, but when you (consciously or unconsciously) seek to benefit from institutional racism you are fundamentally "feeding the machine".
Institutions are ideologically captured by individuals who will general seek to maintain an environment that's to their personal benefit.
Its only fairly recently (wrt mobile phones) that the extent of this individual bias is being held to account.
Yes, AC is just one person but there are many like her.
They have power in who they vote for, the way they behave in their professional life etc etc.
There was in interesting study done in the US where the same CV's (from black Americans) were presented for a job opportunity but one set had typical white names, the other black.
Only 10% got an interview with their own name, but 25% when they were "whitewashed".
Whose hiring the police in the US? In the wider workplace? Where does the power reside?
In the individual and the collective ideology they promote by virtue of their day to day choices and interactions.