Making this particular accommodation has consequences: surgeons turn fat patients away because they don't know how to operate on them. Surgeons can be quite rude in the delivery of that decision, to the point of fat-shaming. While the policy itself might have short-term bona fide reasons, tables can be made bigger and students could be gaining experience with gantries used to move large patients. The medical industry is making perfect the enemy of good in refusing to care for fat patients, and refusing fat cadavers is just one aspect of that.