I'm not entirely sure what you're asking here. I've never said that no context should be used in terms of how wary or careful a cop is. But if, given the same situation and context other than skin color, you take a different action because you perceive someone of one skin color to be more dangerous to someone of another skin color, I don't think it's particularly controversial to say that that action is racist.
You seemed to consider quite meaningful my saying that the action is racist as opposed to going straight into "the cop is racist," but that is an important distinction. You can do something dumb without necessarily being a dumb person. You can do something clumsy without necessarily being a clumsy person. While an action may be racist, I don't think that instantly means the person should be a labeled a racist. Just as there's no hard and fast line you need to cross to go from "smart" to "dumb," there's no hard and fast line you need to cross to go from "generally not racist" to "generally racist." Who one deems to be generally racist is a judgment call based on all their statements and actions (that one is aware of).