This is a fair point, black users could be more subject to police brutality, but like you said, that doesn't fall into the category of crimes. The safety the app calculates is solely related to crimes, and I state in my disclaimer that every user is still responsible for his or her safety/life at the end of the day. The user also has the option to choose between a plethora of route options that optimize his preferences for both safety and speed, they are not being forced to take just one route.