Actually, now that I read the IM exchange (I missed it the first time), I would agree that in his idiot-biased brain, he thought you were flirting with him.
They tell you that a good way to train your puppy not to bite is to say “Ouch!” and immediately put him down, stop playing with him, and give him the cold shoulder when he play-bites. Then you’re puppy will learn quickly that biting results in social ostracism.
Since your Friend-Ron seems to have the brain of a dumb dog, this method may work as effectively. Just sy: “If you are going to be insulting, this conversation can’t continue” and log off your IM program.