The set of rules you internalize to be "normal behaviour" is influenced by your environment. A boy growing up in an isolated household in the woods will have a different model of normalcy, and so when he goes in to town he'll seem "off" to everyone else.
My favourite pop culture example of this is Mose Shrute (Dwight's brother) from The Office (US). He doesn't try to be weird, he just is, because he's grown up in family with weird norms. Similarly the offensive guy in this story probably isn't deliberately pushing aside his common sense, he is just being who he is all the time: someone who is poorly socialized.
It's easy to try to bush incidents like this aside by saying "he knew it was wrong and did it anyway, because he is a jerk" but that deflects from the underlying issue. Socializing makes a lot of devs uncomfortable, so they dont do it. They develop their norms in isolation, and then "go in to town" to conferences like GDC and then set off firestorms. Reacting to these situations in person, you start out trying to convince someone that their comment is rude and wrong. However you end up trying to convince them that their whole model of society is wrong. That is what makes me truly tired.
