If I were to say that "you're ${INSULT}" when you can't hear me, is that not disrespecting you? If I close all my HN posts with "parenoob is ${INSULT}", is that not disrespecting you? Or, to stick with the 2-people restriction, if I closed all my direct e-mails with that statement?

The answer should be fairly obvious.

As for point 2, the fact that teens are currently taught to be sexist doesn't mean they should be taught to be sexist, or that it's OK. Especially not from adults.