"We wouldn't crack jokes about people with arthritis, asthma, diabetes, ulcerative colitis, etc.
We shouldn't crack jokes about people with obesity."

I sort of took issue with the likening of it to obesity. Asthma is a chronic illness that cannot be cured, but in most cases, obesity can be fought and lessened by changing one's lifestyle choices. In addition, jokes are cracked in society all the time about people who suffer from things like asthma and obesity. I'm not implying that it is ethical, but jokes are going to be made about those topics, whether we like it or not. Chris Christie made the decision to step into politics, and people are going to find things about him to poke fun at. If people don't like the jokes about him, there is not much to do about that except move on; those who are into fat jokes are going to find them funny regardless.