Nobody is running into anywhere and "yelling 'retard'", the equivalent of which would be more akin to posting "RETARD" on comment threads all over GitHub. If that's what was happening, most would regard it as spam and would probably agree that the user should be banned (at least temporarily). That's not what happened.
So, while I agree that using "retard" in a lighthearted manner is offensive, and I wouldn't do it myself, I don't decide what others are allowed to say, because I don't want others to decide what I'm allowed to say[1]? Instead, I'll make a choice about who I want to be friends with.
So, while I agree that using "retard" in a lighthearted manner is offensive, and I wouldn't do it myself, I don't decide what others are allowed to say, because I don't want others to decide what I'm allowed to say[1]? Instead, I'll make a choice about who I want to be friends with.
1. https://en.wikipedia.org/wiki/Golden_Rule