Weight, and it's costs, bear a massive penalty in aviation. Charging larger people more per ticket would not be discrimination, it would be reality as imposed by the laws of physics.
Alright but here's the deal. They should put up a WAW (world aviation wrestling) wrestling cage in the terminal, winner gets the cheaper fare looser stays on the ground. That would be fair I think. And winners get to wear speedo style wrastlin tights in flight.