For whatever it's worth to you to know this: being considered thuggish, or violent, or hotheaded, or unreasonable is a hot-button issue for working black professionals. I've had neighbors complain to me that they can't disagree or argue with anything at their office, because as soon as they do, their coworkers start shaking their heads and signaling "there goes the black guy again". Knowing this, you start to see that it is also a privilege to be able to argue, even vehemently, without inadvertently confirming a malignant stereotype about your heritage or upbringing.
Either way one reads that particular point though, I agree that it isn't the most compelling in the story.