If I’m a terrible person to a few people, but nice to everyone, does that still make me a terrible person to everyone?
You cannot follow a certain predetermined style, set of rules, mannerisms etc. to interact with people in your life. With sugar in the mouth and ice on the head, one cannot go cool with everyone.
If I am going to board a train and commuters standing at the doors are not allowing me to enter, I cannot make a kind and sincere request. I have to be slightly rude and exchange negative greetings. You are not a terrible person here.