TBH, my initial reaction was pretty similar to yours. I mean even ignoring the asshole self-righteousness of immediately judging someone's weight without knowing them as a person (and thus the challenges they may be dealing with), at that age most people are having too many health issues to justify being judgemental in that fashion. Particularly so when you consider that at the time this guy grew up we didn't have the understanding we have today (let alone level of public education) regarding how the human body worked.
But given what this person choose to do to others, I also realized that such disrespect was well-earned. So, yeah - i went with the joke instead. I'm sorry that offended you because I agree with where you're coming from, but in this particular case I'm not sorry for doing it as this guy was obviously an asshole in being so manipulative as to start an organization like this. IMHO he therefore disserves all the disrespect he's gotten (and then some).