Shadowbunny
Queen of the Not-Rights
She may have been racially profiling, or she might be like my 85-year-old mother who lives in a high-crime neighborhood who is nervous enough that anyone sitting in a car in front of her home for a prolonged period of time would have her calling the police. And, FWIW, the police who have had to respond to her home (because of burglaries, trespassings, etc) have told her to call them whenever something seems "off" to her."See something, say something" refers to notifying authorities if you see something out of place. The intent is to heighten awareness and help prevent terrorist attacks - such as when someone abandons a backpack containing a bomb.
The woman racially profiled you, for whatever reason. And for what it's worth, I've been approached by the police for being in an idling car in front of the house I lived in, and I'm pasty white. (In that case, I was in a college town, so it was an issue of being profiled as a non-local college student. The police moved on once they realized I was a sober graduate student.)
I'd be irritated with your brother if I were you, and in the future, make sure that you know your rights.
P.S. By the way, one time there were undercover cops on my street, driving back and forth slowly. They looked plenty suspicious to me - I almost called 911.
Don't get me wrong -- I know racial profiling is a thing. But I also know that it could be as simple as a nervous woman who saw someone "sitting in front of her house in a gang relate(d) area” for at least 15 minutes.