More likely mechanism is fat/old people who don’t swim get off a plane on vacation and immediately hop into a physical activity level they don’t usually do in a setting (immersion/swimming) that can cause pulmonary edema even in the healthy/fit.
We put people prone to treat VQ mismatch from pulmonary edema. Read about West zones. Or better watch his 8 lectures, they’re free on YouTube and the most awesome lectures of respiratory physiology ever created.