I agree.
But certainly in the previous admin, for example, the argument would be made that such obesity is a medical disability against which the airline would be discriminating illegally.
We know from stats on this that over 90% of obesity is not because of medical problems like a thyroid issue, etc. Over 90% of them are because they eat too much and dont burn off enough calories.
And regardless, the airlines dont need to make such a distinction, its irrelevant. Its purely a policy that says you can’t take up the space of another passenger based on whatever size seat you are flying in, and if you would, you need to pay for a seat that accomodates you without you interfering with and taking up other passengers personal space.
Its like luggage. The airline doesnt ask why your suitcase is so big, if it exceeds certain size limits, its stowed in the hold, and not allowed as a carry-on.
They could offer fat only flights. Just for them. Like the short bus. It could be the Fat Plane. One seat on each side of a super wide aisle.
The airlines should replace a few rows of the usual seats with bigger seats to accommodate the bigger customers. But yes, those customers should have to pay a higher price.