Some people reach the state that the only part of reality they can still contact, is the ability to get a rise out of someone. If they get a reaction, it's like they are still connected somehow to other people.
I, too, have encountered many severely mentally ill individuals on public transit. One spent an entire 30-minute bus ride explaining to the whole bus how he could tell that I was actually a transperson (with bizarrely graphic detail, which IIRC was transmitted to him by his alien contact) and that I was trying to seduce him with my evil artificial b**bs, so that I could take over his mind, or something.
Another time, a drunk or high fellow berated me for about 100 blocks on the subway for eating when I was already so disgustingly fat. Since I was 38 weeks pregnant at the time, I informed him that in a week or so, I'd be dropping a lot of weight pretty quick. The rest of the train car was laughing at him. He never did figure it out.
Please just ignore this sort of thing. If you are having panic attacks about going into public places, I'd consider this event to be an inciting incident or trigger, rather than a fundamental cause. Please get some care for panic attacks. They are horrible, and they are treatable, and you should not have to just put up with them.