Your friend's friend was trying to get a rise out of you. I've gotten to where I respond the same way. They can believe it or not at this point. I no longer try to wake folks up anymore and refuse to argue with the norms, I will discuss politics with like minded frens only. If people see what's happening, they do. If not, oh well.

I think you handled it great, it's never worth the effort and always leave them with something to ponder.