I suggest that you let go of this incident as it is not worth it to get all worked up over a casual insult especially from a homeless person as you'd be dragged into their mud and they'll win by experience.
I recall some time ago I was walking down the street when a panhandler approached me and asked me for money and as usual I ignored him and when he noticed that I paid no attention to his request, he told me he hopes to see me burned alive to which I replied with a fake smile and just went on thinking how he could thought that insulting me would win me over and make me change my mind and pay him, and that's it. 15 seconds later, I had better things to preoccupy my mind with end of story.
I recall some time ago I was walking down the street when a panhandler approached me and asked me for money and as usual I ignored him and when he noticed that I paid no attention to his request, he told me he hopes to see me burned alive to which I replied with a fake smile and just went on thinking how he could thought that insulting me would win me over and make me change my mind and pay him, and that's it. 15 seconds later, I had better things to preoccupy my mind with end of story.