The narrative is that even if he was joking, he was still being a bigot and deserved it. From the article:  Michael Arthur, the provost of UCL, said in a statement last week that Hunt’s remarks “do contradict the basic values of UCL – even if meant to be taken lightly – and because of that I believe we were right to accept his resignation. "Our commitment to gender equality and our support for women in science was and is the ultimate concern.”  This isn't even a misunderstanding about a misinterpreted hateful statement. This is officially thought-policing. You are not allowed to experience humor at the expense of a protected group.