In article , Ken Blake
wrote:

the solution is simple. if someone is big enough to where two seats are
needed, then that person must buy two seats.

One of my favorite stories is about the woman who, while on a skiing
trip, broke her leg. On the return flight the airline required her to
buy two seats, one to sit on, the other to stretch her leg in a cast
out on.

The only problem was that her two seats were 16A and 24 D.

that sounds like an urban legend.

airlines will move other pax around in that situation, or they'll put
the injured person in a bulkhead seat where there's sufficient legroom
or maybe even op-up them to f.