The point is that, even if Marley is middle class, university educated, sipping on expensive coffee and typing on an expensive computer, that won't save her from being profiled and murdered.
A friend of mine put this very nicely in a recent LinkedIn article. If you are generally perturbed by Marley's article, perhaps his will offer some clarity:
https://www.linkedin.com/pulse/blacklivesmatter-valery-nformba/