I don't believe in giving blanket special accommodations to people who are morbidly obese, as opposed to just conventionally "overweight" as the vast majority of Americans (myself included) sadly are. While certainly some have a genuine medical condition that makes it much more difficult to maintain healthy weight, I am not convinced by available evidence that this is the case for the majority of obese people.
If someone makes the choice to be a very large size, they should not expect a commercial enterprise such as an airline to raise fares for all passengers (by increasing seat and aisle size, for example) in order to accommodate their choice. Nor should they expect other passengers to put up with them occupying parts of their seats. The analogy in the blog posting to a paraplegic whose wheelchair takes up extra space because he "chose to ride a motorcycle without a helmet" is just sad.
The only thing in the referenced blog posting I possibly agree with is that the airline should be more upfront about their policies, so there are no surprises when the reach the ticket counter. However it is a tricky situation to determine, without looking at the person, whether or not they will need an extra seat.
I apologize if my opinion offends anyone. I welcome your thoughts, opposing or otherwise.
Addendum 2/16: I mentioned this post to obadiah and he mentioned that a woman suffered serious injury after being seated next to a very large passenger from several hours on a flight. He's not taking sides one way or the other, just pointing it out.