I see a big difference between rape jokes and using cancer, a word that is only used to describe natural phenomenons (and not necessarily the disease) as opposed to a word that describes a violent despicable act. I do think there is a difference here.
I actually don't mind people using the word cancer to describe something and I think people are a little to gun ho when they are. Do we need to ban people using words of bad diseases to describe something? I think that is a bit overbearing and I'm not entirely sure why people get so upset about that (I understand people die from these diseases, but people die from all sorts of things and jokes are perfectly accepted about all sorts of things but once it comes to cancer people seem to lose their minds). But rape, I could see people getting very upset about that. As the article points out there was a time of people trying to justify rape or downplay what it actually is. I'm sure he didn't mean any harm but it is pretty damn unprofessional to be making rape jokes while you're on that kind of stage.
I don't think this makes it a double standard, because one is clearly worse than the other that it isn't even close. It's like questioning why someone would hire an ex-con who was convicted of burglary but nor an ex-con convicted of aggravated assault. That isn't a double standard.
And he was certainly taken off for several good reasons besides the rape joke, although that was likely just the thing that broke the camel's back. He was turning a top notch show into something really cringe worthy.