The original article made an interesting point which certainly holds true to an extent. However, there is no such think as a rape joke in the sense that there is say an Irish joke. There are jokes which reference rape which are acceptable and those which are not. And everyone will have their own views on particular jokes, part of this acceptability test being how the joke would be received by a potential rapist. Not all men are potential rapists, but perhaps all men are born with the potential to become rapists, depending on how their attitudes are shaped and reinforced. I suspect there are more powerful forces shaping society than stand-up comedy, and that female attitudes to their own feminity and to other females are significant in this respect, but any sort of reinforcement will play into the hands of those already predisposed.
I hope Jo's Friend A was brought up sharply by the reaction his views evoked when stated out loud to someone not inclined to humour him.