They do this a lot with unaccompanied Black women and meek appearing Black men in some places it seems. A lot of women lack any situational awareness, and will sit there and argue with these people not even considering what they could be doing to her food.
Really, if the place exposes itself as being some racist pitstop then there is no real need to be buying any food from the place or hanging around the place at all. You want to cause harm to the place, the best you can do is review bomb the place. Sitting there arguing with them will give them enough time to get their racist police friends to come around and arrest you on trumped up charges. Unless you are actually about that action like Micah Xavier Johnson, it is best to just leave the place and its racists owners and patrons.