Namecalling ("SJWs like you") is against the hacker news guidelines. I would suggest you read them.
Also, it's worth noting that actual, self-proclaimed SJWs (I am one, I know many, and am in their communities) wouldn't have any problem with the joke in question, because it's "punching up", i.e. it is making a joke about social problems in a group that has the systemic advantage. So your name calling isn't even accurate in this case.
> Instead of focusing on the VALUE brought by the author, you managed to dig up one benign joke and went on to discredit the entire thing.
Please point out where the poster "discredit[ed] the entire thing". I don't see them discrediting the entire book, I see them questioning a bit of context around the joke, which is a perfectly valid thing to do.
> Why aren't you ashamed of yourself?
Why aren't you? The poster is asking a legitimate question around the context of a line of the book, and you're insulting them and denigrating them for this.