When keeping it real goes wrong...
Personally, I feel for the eating-girl, although I think that the Ebonic way of responding was everything else but productive.
I travel frequently with trains and subways for work, rugby and meeting friends, so during busy weeks and weekends I often pick up Subway's or boxes of seafood at the train station. Point is, I wouldn't mind if YOU did the same and were to enjoy some greasy goodness on the train.
I can recall 2 specific experiences, both were on the bus. One time an older lady was giving me and some friends shit for eating, we simply changed seats and not a single fuck was given that day.
Another time I was in a hurry and had picked up a giant double patty burger with curly fries tossed in between the buns from my mess hall. When I got on the bus the bus driver cunt started bitching immediately, although I promised I would not eat it until I reached my destination.
Now, I thought about throwing the food at her to prove my point but then my Northern European attitude kicked in so instead I just cursed, got off the bus and then proceeded to enjoy my god-tier food while waiting for the next one. It would have been such a shame to miss out on that marvelous composition of beef, fried potatoes and mustard/ketchup/mayo and up my cortisol over a stupid and pointless argument that no-one could have won.
So yeah, enjoy your food and increase the peace.