Given that African Americans are far, far more likely to be unjustly detained in such a matter, it seems reasonable to assume that mcphage is a white male, given his callous response.
Being racist might seem reasonable, but it is not constructive because you use it to ignore the content of the poster's argument.
Even if the content of the poster's argument is flawed, attack the flaws, not the person.
That word doesn't mean what you appear to believe that it means. I do not hold the belief that one race is superior to another, nor do I hold the belief that society should exploit or disadvantage individuals based on their race. Therefore I am not being racist, nor was my statement.
It's perfectly within the bounds of reasonable discourse to question the underlying assumptions of another's worldview to show that their assertions come from a biased perspective that requires examination.
But you didn't show it. You assumed it, based on their race.