If I call you a retard it's probably not that insulting to you. But it does cause offence in a large group of other people. And those people were not my target. So the word retard is a suboptimal choice for those two reasons.

The other way to use retard as an insult is to use it against people with a learning disability. I don't think that's what you're defending -- verbal aggression by mostly rich programmers of mostly poor vulnerable people.

> I believe in freedom of speech above all.

Not right to life?